Category: design

Thoughts about the Onslaught map generator

Thoughts about the Onslaught map generator

Image by DarkmoonArt_de from Pixabay

With the 2nd Tutorial under my belt, I’ve ben thinking about the map generator which is the subject of the third tutorial. I suspect it will be based on the Empire map generator which you can read about from an earlier blog post.

The difference is that there will only be one continent not several and it has to occupy between maybe 50% and 80% of the specified map size. These are 20 across by 15 deep (small), 30 x 20 across (medium) and 40 across x 30 deep (large). On a 1024 x 768 Window, I managed to fill it with 31 across by 28 deep, so I’ll need a larger playing Window.  The current one is 1024 x 768.

The Empire generator works by first scattering a number of land and sea points in an empty grid then growing layers around each point in the empty cells, stopping when a non-empty cell is found.  I’ll need to modify it so that the starting land points are near enough to form a single continent when grown and reject any map that has 2 or more continents.

I also put Onslaught on my Raspberry Pi and found that it runs a lot slower than on the Hyper-V Ubuntu. I can only put this down to the number of hexagons. a screenful at 1024 x 768 is 31 x 28 hexagons and that requires 868 blits ( each a call to SDL_RenderCopy). Each blit copies 1088 bytes in VRAM.  That’s almost 1 MB of VRAM being copied in itself each frame which is not that much for a GPU but there’s probably some overhead for each blit and I imagine that could be the performance killer.

Kilo- a thousand lines text editor in C

Kilo- a thousand lines text editor in C

Antirez kilo text editorDeveloped by Salvatore Sanfilippo aka antirez and licensed under the BSD 2 licence, kilo is a simple text editor in one file.

If you are learning C and want to see how to write a utility, this might be a good example to follow. Warning though he does use pointers so make sure you’ve learnt them first!

I had a stab at writing one quite a few years ago but it wasn’t very good. I have a suspicion that writing a good text editor depends upon you first creating a good implementation of the text storage. Solve that and it’s downhill for the rest.

I’ve added this to my curated library of C code, on the C Code link on the top menu.


Some thoughts about game AI

Some thoughts about game AI

Image by Dimitris Vetsikas from Pixabay

When I say AI, I mean control logic for computer played units in a game, not Ai as in Machine Learning or Artificial Intelligence. For instance in the Empire type game, that I started (On the Games source link) which has ships and units fighting on land and sea, capturing cities and building new units.

An AI for an Empire type game has a lot of logic to be implemented. I thought about this quite a bit and came up with a task based Ai system. A neutral city is spotted by an exploring ship. If its a transport with armour on infantry then it just attacks the city and hopefully captures it.

If not a task is created. This comprises a number of steps.

  1. Locate units nearest to the city that aren’t allocated to the task.
  2. If the units are on the same continent then just send them to attack the city.
  3. If not Locate the nearest transport and send it to rendezvous with the units at the nearest point to them. Load the units.
  4. If there aren’t any units free then locate the nearest friendly city that’s not tasked with anything and task it to build the units.
  5. If there’s no transport, have the city build a transport after building the armour/infantry units.

That’s just one for task but what if a friendly city is threatened and the tasked units are the nearest. Care has to be taken so that units aren’t flip flopped, getting orders one turn then being pulled away three turns later to a different task.

Each task should be given a time-to-live (say 30 turns), long enough to acquire the resources (units it needs) to do the job and reach the target. The rule then is no diverting units on a task unless a dire emergency (like threatening one of its cities) and those are the nearest.

There’s nothing worse than allocating units to a task then seeing enemy units sail right past unopposed. Writing code to deal with different situations and priorities is not an easy task


I like web games

I like web games

IllyriadNot the Flash type games you get on sites like Kongregate but strategy games like Illyriad, (Pictured) Though you can waste an awful lot of time playing them. The web is an excellent platform for certain of multiplayer games. Heck you can even play games like Quake III which was a desktop game but redone using WebAssembly.

I used to play a strategy game Inselkampf (German for Island war) where you start off with one island and improve it then you can start building ships and invading other islands. I remember getting to the point where I was managing an empire of 80 islands and the only way I could do track all the details was with an Excel spreadsheet. But it was a big time hog, taking up over and hour and a half each day (just mad!) and I stopped playing.

It seems to have closed down a few years ago which is a shame as it was very popular in the mid 2000s. The UK website just has a start Game Over message on it! Searching about I even found a copy of the Inselkampf rules online.

Given my postal games background (I created three Play by Mail games back in the late 80s, two of which are still run today on ) I still have an inkling to create a big web or mobile playable game. I’m not saying I’ll make a £million like  I’m not a great fan of web development (well the JavaScript part of it) but I’m currently studying a Udemy course on Blazor which is Microsoft’s take on C# and WebAssembly.  This lets you create websites in C# running in the browser. And C# I am most definitely a fan of.


The L game by Edward de Bono

The L game by Edward de Bono

The L Game
Image from Wikipedia

I bought a book The Five Day course in Thinking by the author Edward de Bono when I was at University. It included a seemingly very simple two player strategy game called The L Game.  If you’ve heard of the phrase Lateral Thinking that was invented by him back in 1967.

On a 4 x 4 board there are two L shapes and two neutral single pieces. To win you just have to move your L shape and (optionally) one of the neutral pieces so that your opponent can’t move his L shape.

I’ve had a cursory search for C source versions of this game and there are bound to be more than the one I found which was written for an Arduino WifiBoy Pro. There’s a downloadable zip file which contains a file wbpro_chess_L.ino. Despite the extension, it is a C source code text file.

If you are looking for an interesting programming problem then create a computer opponent for a game. The good thing about this is, its so simple graphics wise that you could draw the board in a console with B = Blue, R = red and 1 and 2 the two neutral pieces like this.



Drawing  dungeon rooms using characters

Drawing dungeon rooms using characters

Some roguelike roomsThe final game will use graphics but those graphics will be based on characters, so I’ve started off by drawing a room or two using the provided extended ASCII characters.

Here for example is an 8 x 8 cell room with four inner columns and four possible doors. I’ve used spaces in one and full stops in the other to see which looks better. I think I prefer full stops as you can count them but it’s not a big difference.

╔════╬═╗  ╔════╬═╗  /----\
║      ║  ║......║  |....|
║ ╬  ╬ ║  ║.╬..╬.║  #....|
╬      ╬  ╬......╬  |....|
║      ║  ║......║  \.||./
║ ╬  ╬ ║  ║.╬..╬.║
║      ║  ║......║
╚═╬════╝  ╚═╬════╝

The 3rd room is smaller and roughly octagonal though not as nice looking. I used the normal ASCII characters for that with the two slashes ( / and \ ) as well as # for a vertical wall door and two | for a double door. Here’s a corridor that goes round two corners and then meets another one.

═══     ╔════╦══
   ╚════╝    ║

There are plenty of ASCII character charts and I used this one which describes all the graphical chars making it easy, albeit a bit tedious to draw these in any text editor. There are single box characters as well as the double ones I’ve used. The ╬ character has proved very versatile as it provides not only columns but doors in both horizontal and vertical walls.

It’s noticeable that despite this room being square, it looks rectangular thanks to characters being taller than wide. Also in WordPress, the gaps between lines are more noticeable as gaps whereas in Notepad++ (the editor I used to create these) as shown in the image at the top, these gaps are absent.

Such simplicity- online QR generator

Such simplicity- online QR generator

QR code for Learncgames.comSometimes you come across a design that is sheer simplicity, could not be easier to use and it just works. That QR code you will not be surprised takes you to this very website!

The website that I got it from is Just paste or type in your URL and a QR code appears before your eyes.

This is slightly off-topic for this site and no its not an advert – just a recommendation of a useful website. The thing is QR codes are quite complex (understatement).  This is quite a nice visual description.

This however is a very detailed explanation of how to create a QR code in 10 steps and I wouldn’t be surprised if its the method used in

I remember seeing this explanation a few months ago and no I don’t have a perfect memory. Instead, many of the websites I’ve found are through hacker news. Even better though is this search engine that searches hacker news. I used it to find that QR website.

There are innumerable free QR apps on smartphones so good ahead and verify the QR code!

There’s an elegance about QR codes though it’s not exactly steganography (hiding data or images inside something else) but the fact that you can’t understand it without an app is quite clever. I had an idea once of making a Choose your own Adventure EBook using QR Codes to navigate around a website.

Text and URLs

QR codes can hold a lot of information. Would you believe it if I told you that the QR below has all this blog text (about 230 words) up to the Text and URLs title at the start of this paragraph? Try it!

Also I compressed the PNG file but it still works perfectly. Here’s a screenshot of the QR app that scanned it.

Blog entry QR code

iPhone QR Scan




More thoughts on the design of Rogue like

More thoughts on the design of Rogue like

Unicorn hackSometimes I walk up around 3:00 AM and my mind is abuzz with things like this. Last night was one such night. The first thought was I should stop calling it a Roguelike. There’s a certain set of conventions with those and I don’t want to be limited by that.

For instance here’s an article about things you should or shouldn’t do in designing Roguelikes.

The game (for the next Ebook) is not going to be an all singing all dancing version but will be an MVP in the parlance. That’s Minimum Viable Product,

So if I’m going to divert away from the ‘standard’ then it needs a name. Something evocative like Dungeon Trawler but shorter more catchy.  So I’m going with V.O.R. (Vaults of Ruin) or maybe just Vor,

So onto design aspects. Here’s a list of the features:

  • 10-15 different Monster types with differing melee, range weapons and magic. Can have packs of them, not just one. There is only one player. Should be fun!
  • Simple set of castable spells using a Mana value. It is used up casting spells but regenerates slowly as you move. It can be replenished quicker by consuming potions.
  • No food or water but the character has an energy rating. This is depleted by movement and fighting. Rest or sleep oe rating food replenishes it but I don’t want it to be a major thing. I’m not having deep dungeons with 25 or more levels, but 12 levels maximum.
  • Weapons are sword, dagger or bow. Can switch between them.
  • A few powerful magical treasures.
  • Turn based not real-time. Asteroids is real-time but movement will be restricted to so many squares for you and monsters. You probably won’t be able to outrun the faster moving monsters.
  • Limited visibility can make things interesting. It means the game has to calculate what squares are visible each move.

I was tempted to do away with grid movement; for instance in the Asteroids game, they can move at any angle and velocity and are not tied to a grid. But that might be a bit too complicated so movement will be grid limited and Up/Down, Left/Right and maybe diagonal.

The screenshot is from an open source (.NET Core/C#) web rogue game called Unicornhack.



Now this is interesting – Interactive Fiction

Now this is interesting – Interactive Fiction

Choicve of Games Interactive FictionIt’s not really a thing done in C, although you could do. I came across a site that offers commercial Interactive Fiction. As they put it “text-based, multiple-choice games. ” and “By using text, we can interact with the imagination in different ways from a graphics-based game. We can also allow game designers to quickly and inexpensively produce games in comparison with graphics-based games.”.

Their games aren’t free but aren’t that expensive either typically $5-$8 or thereabouts and you can get them on mobile as well as via Steam. A recent game they’ve just launched has 1.2 million words of text (that includes the game scripts) which is phenomenal considering that most novels are 50,000-90,000 words.  Their games use their own open source scripting language called ChoiceScript which is a very simple programming language.  You can read their online manual (over three web pages) which should take maybe 20 minutes long. You can also play some of their games partly or fully free on the web.

The games are put together through a series of scripts. There’s also a free IDE for creating the scripts from a 3rd party. If you think writing a book is hard then writing an IF (Interactive Fiction) game must be like that but on steroids.

Games like the 1.2 million words one have multiple paths through with different plot lines which aids replayability. This isn’t anything like the Fighting Fantasy books (Name drop: I worked on a football game for Ian Livingstone in the mid 90s) because ChoiceScript has variables. This means that characteristics can improve over time and you can make decisions using <. >, <=, >=,==,!= just like in C etc. It doesn’t have arrays (there seems to have been some attempt at adding them in 2015 but I suspect it didn’t work) but there are subroutines and Goto which lets you create a structure.

You can add graphics but the games I’ve looked at don’t use them much if at all. The pictures are painted with words and this company have a very wide variety of games on sales including RPG, superheroes, science fiction, mysteries, war and pirates amongst others. The game mechanics are multiple-choice questions which doesn’t sound very glamorous but its like reading a book; your mind fleshes out the backdrop. The original Colossal Cave Adventure game is an example of Interactive Fiction and not coincidentally the Awards for Interactive Fiction are called the XYZZY Awards.

As the saying goes “Everyone has a novel in them”. IF is one way to bring it out…


A different way of generating a dungeon level

A different way of generating a dungeon level

Image by Artie_Navarre from Pixabay

I talked previously on how I generated dungeon levels by splatting down squares and circles of random sizes and then linked them together by corridors.

But another way that might make levels look not quite so procedurally generated is to first compile a catalogue of dungeon rooms.  These are “hand drawn” in a master text file, perhaps something like this:

*        *
=        *
*        =
*        *

Where * marks the walls,| a possible location of a vertical running corridor and = the same for horizontal running corridor. Each entry in the catalogue has a size (vertical, horizontal) e.g. (6, 11) for the room above and the generator program has to find space for this and then see which of the four doors it can connect to.

You can decide if you want a dead end room or one with more doorways. Any unused doorways are just replaced with a * for wall. Single door rooms might have a secret door that the player has to first discover and unlock/open.

When the generator starts, it reads in the master file, builds a list of rooms and then starts using them to generate levels.

The advantage of the catalogue method is that you are free to create as many room sizes and shapes as you wish and they don’t have to be rectangular or square. Yes the level is procedurally generated but using this methods makes it look less so. You can have very small rooms (2 x 2 anyone?)  or massive hallways with lots of columns.