Epic Megagames (formerly Potomac Computer Systems) was founded way back in 1991 (or thereabouts) by Tim Sweeney, to market his new shareware game ZZT. ZZT became a tremendous hit, popular with fun-loving, computer-savvy people who enjoyed it's unprecedented in-game editor with built-in object-oriented scripting language. Epic held a contest for the best user-created ZZT worlds, many of the winners of which (including Allen Pilgrim) became Epic employees.
In the next several years, Epic grew immensely. They began producing a tremendous, disparate body of shareware, a good portion of which was worthy of Epic's trademark quality, enjoyability, and originality. Some wasn't, of course.
Anyway, they went into a quiet stage around 1997, during which they pretty much just released Jazz Jackrabbit 2, and maybe some more pinball games. Turns out they were turning commercial behind all our backs, and took the "Mega" out of their name.
ZZT: The classic. Frickin' brilliant. Later came Worlds of ZZT (contest winners), Super ZZT (bigger boards, square graphics), and something else, I forget.
Jill of the Jungle: fun side-scrolling jumper action game. 3 episodes
Solar Winds: decent Sci-Fi RPG/action game. top-down, 2D.
Kiloblaster: Galaga descendent with OK graphics and good sound
Overkill: Yet Another Vertical Space Shooter
Jazz Jackrabbit: Fairly well-done Sonic the Hedgehog rip-off. sequel to follow, slightly more popular
Tyrian: scrolling airplane shooter. Like Apogee's Raptor.
Epic Pinball: Great pinball games, many follow-ups
ElectroMan: platform shooter, pretty dumb.
Heartlight: some tile-based puzzle game with a little elf
Robo: another tile-based puzzle game
Brix: addictive tile-based puzzle game
Castle of the Winds: Great, simple RPG for Win3x. The Ultima of shareware RPGs
Dare to Dream: Enjoyable Win3x image-based adventure game with a surreal storyline.
One Must Fall: Fighting game with robots. About as good as they came on the PC at the time; not that great.
Seek and Destroy: 2D helicopter action game
Radix (Beyond the Void): 3D ship shooter, kinda Doom mixed with Descent. Never popular (I think)
7th Legion: Command and Conquer knock-off. Dumb AI.
Many of these games are available for download in various spots (no longer from Epic), or from http://www.epicclassics.com if you want to pay money for some retro gaming action.