Very compact Tetris game for those who want to play where/when they should not: only a tiny gaming area (even 40px high) your headmaster will hardly notice (in case, just press Q or Escape).
Tundra is an extensible, open-source game engine which replicates Lemmings (written originally by DMA Design). Players must save thousands of adorable, tiny rodents from certain death by helping them create a pathway to the exit.