You can play Poom right now in your browser, using the arrow keys to move and either X or spacebar to shoot, with Z to strafe or open doors. (It also supports mouse, and other control schemes are available.) There are six original levels and they all nail the feeling of original Doom. So does the music, which is chiptune covers of the original soundtrack. It’s the work of Frederic Souchu and Paranoid Cactus, and it’s rad as hell.
Thanks for the heads-up, PCGamesN.