Any ideas?

Yes. Duke Nukem 1+2 and Earthworm Jim 1+2.
Extra recommendation for Secret Agent.

Superfrog! Sometimes super-frustrating (hitting a spike and dying instantly) but it's really enjoyable with nice music.

Its silly password system doesn't help either.

True, but nowadays you can use Internet and simple check password for levels you've properly beaten. Personally i wouldn't consider it cheating.

Not on GOG, but Jazz Jackrabbit is a personal favourite of mine.

Also some awesome freeware titles: Alien Carnage and Jetpack.

As for GOG games, I would recommend Rayman Forever.

Bio Menace and Realms of Chaos

Alien Rampage is great if you don't mind abandonware sites(that's the only place where you can get it) .



https://www.youtube.com/watch?v=0cZepk1eU5I

Conan

Lode Runner

Okay so those were kind of pre-DOS but those games raised me. :D

TBH I would get an Amiga emulator fired up (or (S)NES/Sega) and go from there. The 2D platformers were far superior on those platforms.

But for PC I second Jazz Jackrabbit and Earthworm Jim. And should you feel more like running and gunning than jumping - [url=http://en.wikipedia.org/wiki/Abuse_(video_game)]Abuse [/url]is pretty neat. There's a free port available somewhere, unfortunately the homepage seems to be dead.

Great ideas everyone!

Hocus Pocus.

Aren't Cosmo's Cosmic Adventure and Crystal Caves DOS?

I second Jazz Jackrabbit, amazing visuals and music but maybe a bit too tough to play.

Other recommendations are: Another World and Flashback which are cinematic platformers, The Lost Vikings which is a puzzle platformer and Blackthorne which I think are free on Blizzards site, Abuse which is also freeware I think, Duke Nukem 1&2, Secret Agent, Cosmo's Cosmic Adventure.