Simple :D

Blood Omen: Legacy of Kain

[edit] played the demo ages ago, but could never get the full game working (Vista). Always froze up with the bartender walking back and forth...

I know I should wait for confirmation, but I'm very confident...
proof: http://www.mobygames.com/game/blood-omen-legacy-of-kain/screenshots

I'll attach the next one.

Right!
Very difficult game indeed. I've played it only after Soul Reaver's release, founded in a offer can in an old school corner shop.
Anyway, it's your turn :)

Adventures in Math?

You're in the right area, but that's not the right answer.

I actually used to play both this and Adventures in Math in my youth. I guess my parents thought it was educational. Not sure how much they helped, I was more interested in Alley Cat.

He he, Alley Cat ... That would have been a nice one, too. Completely forgot about it.

More tips please -_-

Here's another screenshot.

Kinda hard to find any more though, or at least any others that would be more helpful.

I'm surprised that kalirion didn't have another guess considering how close he was.

The only changes I've made to the screenshots was to remove the name of the game.

Monster + Math = Monster Math?

Correct!

See... it wasn't that hard, was it??

I think this one should be easy enough.

Redline - Gang Warfare: 2066 ?

Uhhhhh.. probably?
I just know it as Redline ;)

Great game indeed
I had played the demo before the release of the game but I never see a retail box in the shelves, physically so I've bought it not too long time ago in ebay. The funniest part is that I've publicized the demo to my friends, wich one of them was a friend of my brother: I don't know how or why but with the same demo installer his installation was full with all the levels!
Edit: of course, the name is correct :D

Wikipedia:
Redline is a 1999 post-apocalyptic combination first-person shooter/racing video game for Microsoft Windows. It was developed by Beyond Games and published by Accolade. In Europe, the game was known as Redline - Gang Warfare: 2066. This was the last game Accolade published before being acquired by French publisher Infogrames.

I only remembered the game as Redline as well. In fact, despite having bought this game back in the day, I never played it. Don't know why, but recognised it from the graphics.
Ok, nothing clever sprung to mind, so an easy one:
http://i54.tinypic.com/1zcfprb.jpg