does anyone here play the free games gog has to offer? if so, which ones are good and which ones are totally not worth your time?

Beneath a Steel Sky is the best.

That's the only one i've completed. And it's awesome.

Savage Empire?
Tyrian?
Ultima 4?
Martian Dreams?

9 free games, at least 5 of which are excellent. They are worth your time I'd say.

I did play all of them except that Teenagent thing( no idea what the hell that is, not really interested finding out to be honest) but Beneath a Steel Sky is the best of those, then Tyrian :)

don't get me started on savage empire. what waste of hard drive space. I'd rather stick my head into a pool of urine that has electic currents going through it then play that awful peice of junk that is savage empire.

the mars one however, is excellent!

and teen agent is pretty fun, a little hard in my humble opinion but if you good at beneath a steal sky, you'll like teen agent.

ultima 4 is perhaps one of the oldest games ever, and has a huge list of commands that i couldn't find anywhere on gog, thus, made it nearly unplayable. I played the first one as it came with this cd of full version dos games in a pc gamer magazine long time ago, and had a lot of fun. the point is, i know many of the more important commands off the top fo my head, and thus, can enjoy that old peice of nostalgia.

Why do you find it so bad? I've actually enjoyed it quite a bit, before I got tired of fighting with old-game design and gave up. But what I've seen I've really liked.

Ultima 4 has a reference card with all the key commands in the extras section, as well as the manual, spellbook, and map.
The only free games I finished were Lure of the Temptress, Beneath a Steel Sky, and Treasure Adventure Game. Really enjoyed the last 2.

I tried a few of them.

Treasure Adventure Game seemed a bit lacking in the story area, and it made it hard for me to keep playing. It was like it wanted to have a lot of charm, but fell just short of having any of that charm other than a small amount from the graphical style. I respect the developer for working as hard as he did on it over the 3 years or so it took to develop, but it just didn't really grab me.

Ultima 4 is really obtuse, so I found it hard to play.

Beneath a Steel Sky thinks on a different wavelength than I do, so I had issues with it, but I really liked what I did manage to play before getting stuck. I can definitely see why people like the game so much.

Lure of the Temptress seemed near impossible to get past that first part. After trying a dozen times and missing by inches, I gave up.

I never tried Teen Agent.

I couldn't get the Worlds of Ultima games to work on my other computer before it died and I forgot to try after the fixes.

EDIT: Oh, right, Tyrian. I tried Tyrian. I liked the idea of it, but it seemed to lack the "punch" of games like it like DoDonPachi, Ikaruga, etc.

Out of the ones that I've played:
Beneath a Steel Sky: Excellent adventure game, interesting plot, good puzzles, nice (if a bit low res) graphics.
Tyrian 2000: Really good. I've never played a 2d shooter with so much content in it, and most of what is in there is good.
Ultima 4 Has not aged all that well, but it is still interesting. Don't be afraid to use a guide if you start to feel frustrated while playing this game.
Lure of the Temptress: Not that good. It is not a horrendous advenutre game, but there are enough better ones out there to make this one skippable.
Worlds of Ultima: Savage Empire I hate the Ultima 6 engine. I HATE THE ULTIMA 6 ENGINE.