Master of orion 3 is the only terrible game that comes to my mind. I loved part 1 and 2 but part 3 was a setback in every aspect. The only game I ever ragequitted was turn-based 4X-game. No other online-game was able to frustrate me like that.
The other terrible games I've played are long forgotten.
Corruption time had a unique art style and a nice setting
Ecchhi Sensei was an interesting version with a school setting but way too many girls
Naked holidays was aso a nice game