Well, I'm guessing that it isn't Monopoly.

The fighting and cubes (probably dice?) makes me think of Dungeon Siege II.

The squares make me think of any old-school dungeon crawler, like Legend of Grimrock.

Hmmm, Dungeons & Dragons or The Dark Eye?

Hero Quest

*Ding, ding, ding!* Well done.

Another very easy one.

Commandos!

Halt, wer ist da? Ein Verletzter! Alarm! Alarm!
Uhm, I mean YES!

Yay! Good drawing, by the way...

Thanks.

This game should be on GOG, but isn't.

Sub Culture?

Geez, that's a damn fine guess, but no. That might be the fault of my inept drawing of the watercraft being more like Sub Culture than what I had in mind. I'll take the blame for that.

So, it was aquanox ?

He said it's not on GOG yet, so it would have to be Archimedean Dynasty aka Schleichfahrt (if he meant a title from this series).

Yes! Archimedean Dynasty, the Privateer of the sea! The predecessor to Aquanox. Congratulations :D

Another easy one.