Diablo 3. Like EU4, I heard about it, got really excited about it, kinda forgot about it for a while, checked up on it a few months later and then got super excited again.
After being stabbed in the heart by Diablo 3's real money auction house/garbage plot/Diablo looking dumb/ TER-ROAR/jon-DARRRR/et cetera, I wasn't sure if I could ever be excited for a launch again, but I loved the EU4 demo so now I'm just excited again
...title said "last game you were this excited for", so didn't list Skyrim. Excitement doesn't describe my feeling for that game. Only game I've ever gone to a midnight opening for, went to bed at 2am, couldn't sleep until like 4am, woke up at 6am with no alarm and heart racing so just decided alright lets do this!