AIRPLANZ

2 players - 1 Gameboy ROM written in Assembly

This repo is part of HomebrewOwl.GB projects collection. Download the latest version here.

The idea

After I got a taste of how Nintendo DS programming feels like, I realised that I was stubbornly avoiding the entire magic-driven world of retro graphics or, more exactly, the tiles-sprites ecosystem. The NDS's variety of background and video modes is a discouragingly hostile place for a newcomer like me who thought that displays do nothing but getPixel()/setPixel() routines. So (during one of my shower thoughts) it popped into my mind: Hmm... Why don't I turn my attention to an older architecture in order to figure out how things actually work?. And Gameboy was such an appealing target.

Several weeks passed since then without having researched anything, not to mention writing even a single line of code. Why? 'Cause I lacked motivation. Till one day when my annoyed subconscious suddenly roared: 'Too easy for you, boy??? Alright then... Just write it in ASSEMBLY!'. 'Say no more - Challenge accepted!', I replied to myself.

The last thing to decide on was... what game should I write? I've always dreamed about makng my own Pokémon-like scroll RPG game, but I wanted something faster to make. Many of the popular arcade-type games like Snake, TicTacToe, 2048 and even CHIP-8 already have Gameboy adaptations (or "ports", to sound more technical). Then I found the 'spark': it was with me everytime, everywhere. And I loved it. It's the game that, just like the guy in this post states, "In Romania [...] is very popular among students and it is played with pen and paper during recess and during class" - and I merely confirm that. So let's do an Airplanes game for Gameboy. Wait a second... A, I, R, ... (grown-up N•I•L uses his fingers to count all the nine letters). Oh, that's odd. Let's make it AirplanZ.

How to build

git clone https://github.com/NotImplementedLife/AIRPLANZ --recursive

cd AIRPLANZ
make

Make sure RGBDS is installed and exists in your %PATH%.

How to play

For those familiar with Battleship, it's basically the same game, but with airplanes and slightly modified rules. Each player has a 10x10 board on which they place 3 airplanes each like in this picture:

Then, the planes disappear (on pen'n'paper version, use a new empty board) and you have to guess where the opponent's planes may be. That means you choose a cell (on pen'n'paper version, they are labeled A1-J10, on Gameboy I didn't find this thing necessary) and the software (the opponent) tells you whether you missed, hit a plane part or its cockpit (in this situation, the whole plane is destroyed). Everything is illustrated below:

Note:

• "X" = missed
• "O" = hit
• destroyed plane appears dotted

It's a 2 players - 1 console game, so you have to pass the Gameboy to your opponent each turn.

1. Title screen appears. The first player presses A and the board will be loaded. Planes need to be moved (D-pad) or rotated (Select) such that no two planes overlap in the end. Press A,B to commute between airplanes.
2. When ready, press Start. Be careful, once you pressed it, you can no longer edit your board configuration, unless you hard reset the game.
3. A message will appear telling you to pass the Gameboy to the next player. Player 2 presses start and sets his/her board, then presses Start and passes Gameboy to Player 1.
4. Player 1 presses Start and opponent's board will be shown. Player 1 chooses a cell to attack, then presses A. Player 1 passes the Gameboy to Player 2, who does the same thing.
5. Both player repeat the process until one player destroys all the 3 planes of the opponent.

screenshot from Android emulator

Credits

• GBDev community for their kindness and willingness to help uninitiated people like me in terms of GBz80 (or whatever want to call it)
• alexhulk2002 for his idea of one-Gameboy gameplay. If it wasn't for him, I'd still be looking for ways to make two Gameboys communicate through a link cable, as I originally planned this project would do.
• the anonymous hero who invented this game in its paper format
• Special thanks to Antonio Vivace for publishing the ROM on Homebrew Hub. As a matter of fact, AIRPLANZ is the lucky occupant of the 500th entry of the database 🎉

Final thoughts

This is a proof of concept. All I meant was to be functional. Performance wasn't a matter, so I could miss as many vBlanks as I wanted. The code is terrible. It gives me headaches. But I know that nothing is perfect and never could it be... I probably won't update AIRPLANZ unless I find some major errors/bugs/glitches that need to be fixed. [Actually GBZ80 programming is very addictive tbh :) ]

Linked

• Gameboy ASM Examples - the playground I trained on for this "final boss" ROM.
• HomebrewOwl.GB - check out my other Gameboy projects
• Graphics were made using my Tileset Generator