An instant favorite. It’s everything you could possibly want in a 90s throw back, minus the 2D sprites and plus the HD resolution, mouse aiming, creative level design, uniquely simple but somehow freighting enemies, frantic play and addictive gameplay. On some levels I would even try to see how many enemies I could get fighting each other, something I did all the time with Doom. And yes, they do fight and kill each other. It's glorious.