These are in no particular order. The spirit of the game to me is wonder, silliness, getting out of tough scrapes, and having a story to tell that makes others wish that they were there.
Dungeonslayers can be downloaded here.
The Expert Rules can be purchased here.
Dungeon World can be purchased here
Slumbering Ursine Dunes can be purchased here
The Lost Caverns of Tsojcanth can be purchased here
Risus can be downloaded in multiple formats here
There are so many more things I could post like the cover of the 1st Edition Manual of the Planes, the cover of any Tekumel game,the cover of Warrior, Rogue, & Mage, Hackmaster, Renegade Legion, TSR’s Marvel Super Heroes, Champions, Shadowrun (recent edition), Usagi Yojimbo, covers of all the Sine Nomine games, and Bushido.
Last and not least, the real spirit of the game is conveyed by ‘zine covers are all kinds. I mean Crawl, Gongfarmer’s Almanac, Hack, Crawling Under a Broken Moon, Wizards Mutants Laser Pistols, and Black Pudding.
p align="left">I should create an album with all the covers that put me in the spirit of the game. I ran out of space here and I stretched the definition of cover a bit. Next time, I’ll be sure to do that.