Older D&D style game, Neverwinter Nights 2 Trilogy. Great game. Will run great on the 750 Ti.
Battle for Wesnoth - Fantasy style Turn-base strategy. Open source and free. Very challenging on hard difficulties.
League of Legends
Old school D&D remake - Baldur's Gate & Baldur's Gate 2 - available on gog.com
Mass Effect Trilogy
Counter Strike Global Offensive
Crysis - very GPU demanding
just to name a few.
and just bought Watch Dogs pretty cool - very unoptimized for PC...waiting for patch.