Chessyka is a chess game for Gameboy Advance developed by Kay Hornig. He mainly wrote it to learn how to code on a GBA. The AI use alpha-beta-search, 0x88 and bitfield representation of the board, hashing with zobrist keys and moveordering. There is an opening book included, but currently this is only a proof of concept and contain only some minor variants of the french defense. A special feature is the possibility to enter a custom position. Although there is only a very simple check for plausibility! Chessyka is aware of all chess rules, including "en passant", castle, 50-moves-draw and 3x-repetition-draw. Currently only the english language and basic undo of moves are activated. The multilanguage menu (english, german and espanol) and the advanced undo/redo feature are disabled.