Fairtris is a video game, a clone of the 32-year-old Tetris® game produced by Nintendo for the Famicom and NES consoles, designed for modern Windows systems. Fairtris is not an emulator — it is a full-fledged game, created from scratch in Free Pascal language (using the Lazarus IDE) and with OpenGL support via the SDL library. Thanks to this combination, it is super-fast and ultra-light.

This project was initially created as a tool to test various RNG algorithms, but after some time it turned into a complete and rich video game that provides lots of fun. However, since Tetris® is a proprietary brand to which The Tetris Company is entitled, Fairtris is not a product — it is a knowledge base for those who would like to know more about the internal mechanisms of the classic version of this game.

Important features

• implementation of gameplay mechanics compatible with the Nintendo Tetris® game,
• DAS mechanics fixed and spin buffering added, making the controls fabulously responsive,
• extended mechanics with basic wall kick, hard-drop and multi-spawn soft-drop,
• support for EIGHT regional versions of the game, including original NTSC and PAL versions,
• support for as many as SEVEN random piece generators, including the classic RNG,
• support for free marathon and speedrun modes, qualifications and matches with same piece set,
• the ability to start the game from any level up to the killscreen,
• the ability to play on a keyboard or any USB controller (with input mapping support),
• supports window mode and exclusive video mode,
• support for additional meters, such as TRT, BRN, as well as gain popup,
• stores the best results for each game region and RNG type,
• has a pause menu with the ability to quickly restart the game and change settings,
• shows the game summary screen after each game,
• support for two themes (minimalistic dark and classic skin),
• possibility to use it with NestrisChamps and MaxoutClub,
• it's light and very fast — should run smoothly even on a heavily loaded PC,
• it is fully portable, no installation required,
• and many more!

Snap source: https://github.com/chronoscz/Fairtris