2010 Mac mini. That is NVIDIA 320M, right? Do you still run Mac OS X 10.6 Snow Leopard or have you upgraded to newer OS X?
Some Mac OS X Games from last decade that Mac Mini should Handle:
I've tested most of them on OS X 10.8.5 Mountain Lion
(MAS = Mac App Store, DVD = "Go to Amazon.com")
Aspyr
Doom 3 (MAS)
Quake 4 (MAS)
Prey (MAS)
SW Jedi Knight 2, SW Jedi Knight: Jedi Academy (MAS/Steam)
Command & Conquer Generals (DVD, Requires UB Patch, maximum OS X: 10.8)
Call of Duty, Call of Duty 2, Call of Duty 4 (MAS)
The Sims 2 + Expansions Close Combat: First to Fight (DVD, Requires UB Patch)
RollerCoaster Tycoon 3 (MAS)
Civilization 4 + Expansions, Civ4: Colonization (MAS)
NeverWinter Nights 2 (DVD)
SW: Empire at War (MAS)
Company of Heroes (MAS)
Feral
(Feral =
https://store.feralinteractive.com)
Worms 3D (DVD, Requires UB Patch)
The Movies (Feral, MAS)
Tomb Raider Anniversary (DVD)
Fable: The Lost Chapters (DVD)
Battlestations Midway, Battlestations Pacific (Feral, MAS)
Sid Meier's Pirates! (Feral, MAS)
TOCA Race Driver 3 (DVD)
Rome: Total War (Feral, MAS)
Brothers in Arms: Double Time (Feral, MAS)
Borderlands 1 (Feral, MAS)
DiRT 2 (Feral, MAS, low details)
Sid Meier's Railroads! (Feral, MAS)
Tropico 3 (Feral, MAS, low detail)
GRID (Feral, MAS, 8GB RAM, low detail)
MacSoft (Dead publisher)
Age of Mythology (DVD, Requires UB Patch)
Halo (DVD, problems with OS X 10.9)
Unreal Tournament 2004 (DVD, Requires UB Patch)
Close Combat: First to Fight (DVD, Requires UB Patch)
Zoo Tycoon 2 (DVD, Requires UB Patch)
Age of Empires 3 + Expansions (DVD, Requires UB Patch)