Simple Direct Layer (SDL for short) is a framework most commonly used for games. Apps made with SDL may not look like Haiku programs, but they do work!
Ablockalypse - Tetris implemented in SDL2
A Borg Alert - A top down scrolling space shooter
Blue Cube - Yet ANOTHER Tetris clone
Brick shooter - A positional game
Brogue CE - Welcome to the Dungeons of Doom!
C_Flashcards - A minimalist flashcard app
cdvst - Certain Death via Space Things
Jet Set Willy - Fullscreen SDL port of a 1980s game
MandelbrotSDL - A fractal viewer
Manic Miner - Fullscreen SDL port of a 1980s game
Missile Command - Save your cities!
Moon Lander - Land a rocket on the moon
MunchMan - It's Pac-man, all right, but fast and claustrophobic
rterm - A terminal emulator
Savior Ship - A 2D fighter ship game
Space Cadet Pinball - SDL version of a pinball game bundled with Windows.
Starfield95 - This demo recreates a classic Windows95 screensaver
Tanks - Like Pacman, but with tanks!
tcmenu - A simple, lightweight menu application using ncurses
Tea Time - A CLI utility to schedule a break for tea
Twin Distress - Block matching game