Play open source games
A freeware game is a game you can play completely for free with no payments needed: no microtransactions, no subscription fees.
OpenTTD
simulation / management
Windows, Linux, Mac OSX, Free BSD, SolarisOpenTTD Team
Battle for Wesnoth
strategy / turn-based tactics
Windows, Solaris, Linux, Free BSD, BeOS, Amiga, Mac OSX, iOS, AndroidDavid White
Cataclysm: Dark Days Ahead
RPG / roguelike
Windows, Linux, Mac OSXKevin Granade
Unknown Horizons
simulation / city building
Windows, Linux, Mac OSXThe Unknown Horizons Developers
0 A.D.
strategy / real-time strategy
Windows, Mac OSX, LinuxWildfire Games
Angband
RPG / roguelike
Windows, Mac OSX, Linux, DOS, AndroidAngband Development Team
Dungeon Crawl Stone Soup
RPG / roguelike
Windows, Mac OSX, LinuxDCSS Devteam
Hurrican
platform / run and gun
WindowsPoke53280
FreeCol
strategy / 4X
Windows, Mac OSX, LinuxThe Freecol Team
Alien Arena
shooter / first-person shooter
Windows, Linux, Mac OSXCOR Entertainment
TomeNET
RPG / roguelike
Windows, Linux, Mac OSXTomeNET team
Warsow
shooter / first-person shooter
Windows, Linux, Mac OSXWarsow Team
Widelands
strategy / real-time strategy
Windows, Linux, Mac OSXWidelands Development Team
Mirror Magic
puzzle
Windows, DOS, Linux, Amiga, Android, Mac OSXArtsoft Entertainment
Dungeon Craft
RPG / old school RPG
WindowsDungeon Craft Team
OpenClonk
platform
Windows, Linux, Mac OSXOpenClonk team
OpenRCT2
simulation / management
Windows, Linux, Mac OSXOpenRCT2 team
Simutrans
simulation / management
Windows, Linux, Mac OSX, BeOS, AmigaSimutrans Development Team
Xonotic
shooter / first-person shooter
Linux, Free BSD, Windows, Mac OSXTeam Xonotic
Sextris
puzzle / tile-matching
browserSextris