Legacy of Kain game series for it's great story and voice acting. Funny thing - I've never finished 2 out of 5 titles in this series, while other 3 were played by me from the beginning till the end at least 5 times each.
Earth 21x0 - x={4, 5, 6} π polish real time strategy games, my first real PC games out of those I've played mainly the middle - 2150 games (there were 3), of which my favorite is The Moon Project (again, the middle one π)
Gothic - my first RPG. I know that graphics in first two parts is not too great, but it was the best one I've seen in any game of that type at that point, until my friend lent me Morrowind.
Carmageddon - just because π I've started with C2, now played them all.
GemCraft - very long and very grindy tower defence games (only only one on steam, all available in flash versions)
for single titles
HoMM III and IV - started with 3rd part, 4th was good as well, but I couldn't stand 5th one. tried 1st and 2nd not so long ago but I've played them only to check what those were (I've completed only main story/campaign).
TES III: Morrowind - why single title? because I haven't played the rest. simple as that, why here ? ... don't ask, go play it π
Croc 1 - I am still waiting for digital PC re-relase (GOG, help, give us Croc 2 as well, would be glad to try it). I don't know if there was any better 3D platformer for PC, surely I haven't played one.
Hitmanβ’ - a Y2016 title from this big franchise. I haven't played previous installments before that one, but now I've already completed Absolution (good one), and started the very first part but haven't completed yet - can't force myself to go back π this game is really old.
Gabriel Knight 3: Blood of the sacred, blood of the damned - again, I've played only this single title out of 3. I really liked the story, music (intro theme). Funny thing, I've played it soon before Dan Brown released his DaVinci's Code. Both stories really have a lot in common.
