Gem Square (Android) updated to 1.2.5

Just a quick note, that finally Gem Square for Android got a small update. The most notable features are a fix for the high score system and a main menu button to enable and disable sound. I also updated the facebook integration.

Web-Version of Gem Square

With the development of the web service for my own high score system I decided to also create a web version of Gem Square. You can play it at webgames.mystictri.com The game is implemented as a Java Applet and uses the same game code as the Android version. It has its own weekly and all-time high score board that is viewable on the web page. I think the mouse interface works quite well considering that the game was designed for touch screen devices. Give it a try and let me know what you think.

Building my own global High Score system

I just released a new version of Gem Square (1.2) and with this version my new high score system is going live. In the older versions I used ScoreNinja that worked ok but I missed some important features like saving your nickname and multiple highscore lists. So I decided to build my own global high score system using Googles app engine. It now supports multiple lists per application which I use for Gem Square to provide an all-time highscore lists and a weekly list. The details of the high score system are quite simple. It is a servlet written in Java that recieves the highscore posts via HTTP, stores them in a database and returns the top ten for each list. Now that I have my own system I can think of many nice features I want to integrate in the future. One of this features would be to actually show the current high scores on a web page.

Push Down! - Update to 1.2

I just released an update for my puzzle game Push Down. After some considerations it now contains a new level selection scheme. I think the old one with a linear progression did not fit very well to the rest of the game structure. So now you can select each level in the game directly from the start but they are still ordered roughly by difficulty. Additionally I introduced a new rating system for each map based on the number of completion steps. So now the less steps you need to complete a level the better your rating gets. The best rating you can get are three stars and the worst a C (but you really have to wander aimlessly in a level to get a C). And finally I decided to exchange the black background to something more colorful. Here a two screenshots of the updated game.

If you have any comments please let me know.

Gem Square - Procedural Gems

I just released my new free game Gem Square for Android on the Android Market. It is a very simple 'match 3' game with square gems. One of my goals when deciding to develop this game was to start a simple project where I could use my open source texture edtior NeoTextureEdit.
I hoped that using the editor on a real (but small) project helps me to identify parts that can be improved. The result after finishing gem square: it worked :-)

So here is a screenshot of the final NeoTextureEdit project with the gems from the game as procedural images:

It might look a bit confusing, but for such a small project it worked really well. The most important feature that was missing when I started the project was a way to automatically (i.e. via a shell script) export images from the texture project. This is now part of NeoTextureEdit and works really well by adding filename prefixes to individual nodes to mark them for export. More features that came to my mind during the project and that are now on my todo list are automatic graph layout and merging of redundant nodes.
At the end of the project I have to say that using procedural representations for game graphics when possible is really a time saver. The images are resolution independent and you can make small changes to all images with a single click and they get exported automatically. This hugely improves the workflow and shortens iteration time.

Push Down! is NP-Complete

A friend of mine (nick: diophant) has proven that my android game Push Down! is NP-complete. The proof is surprisingly simple and he did it by showing how the boolean satisfiability problem (SAT) can be mapped onto a level in the game. Instead of a formal proof here is an example:

The equation is:

(A v B v C) (-B v -C) (-A v B) (-B v C)

and the corresponding level is here:

Each literal in the equation is a color in the map (A = green, B = blue, C = yellow). Due to the linked-block property of the game, same colored blocks can only move together. The three blocks on the left are the switches to set each literal to a value of either 0 or 1. Currently they are all set to 0 and moving them up would set them to 1. The four columns on the right are for each term in the equation. If you can find an assignment of A, B and C so that the equation evaluates to TRUE you can find a way to the exit otherwise not.

With this construction it is easy to see that you now can build a map for any given boolean equation but they would quickly grow in size and would be rather confusing to solve. Nevertheless this shows that Push Down! is indeed NP-complete.

If this was a little confusing here is some more detail. The equation above means 

(A or B or C) and (not(B) or not(C)) and (not(A) or B) and (not(B) or C).

The first column is currently blocked completely (A, B, and C are 0) but it is enough to flip one of the literals to make a way and also make the first term in the equation evaluate to TRUE. For example let us flip C (yellow) by moving it up. Now the first term evaluates to true and actually the whole equation evaluates to true as we now can walk the the end of the maps on the right.

If you have any questions or comments write them down below in the comments.

Push Down! Game Page

Push Down! Update to v1.1.0

A new update for Push Down is released. I added a new challenge mode with 14 new maps. These maps can be played individually and in any order. On successful completion you get some fruit. More information can be found at the official website www.mystictri.com.