I don’t recommend games where the bitmaps originated elsewhere and were ported lazily to the Mac. Not good showcases.
Cosmic Osmo, The Manhole, and Spelunx and the Caves of Mr. Seudo all have superb 1-bit artwork. Cyan made their own halftone patterns, which blend smoothly into one another. I recreated these patterns in FullPaint for use in my own doodles.
Before he made the Dark Castle games, Mark Stephen Pierce did the handsome demo animation for VideoWorks and VideoWorks II.
Both Frankie’s Dungeon and Creepy Castle are lookers, though the latter has better interstitials. Its main title screen is just smashing.
Trici Venola’s character art for The Comic Strip Factory is juicy stuff. I wish she had made a game.
A lot of love went into the sprites for the black-and-white version of Battle Chess.
Arkanoid is an outstanding arcade conversion. It has fast action and flicker-free animation.