I’m not what you would call a “gamer” in any way - for me, it’s just Tetris and Jumpman, the latter of which is an 8-bit-style platformer updated for today’s computers. Jumpman (which is both free and Mac/Windows/Linux compatible) has a level editor, and I just discovered the many level packs that fans of the game have designed for it.
My favorite of the bunch is easily Jump Story, a series of more than 100 levels designed by Peter Mawhorter. It gets pretty crazy towards the end, and I really enjoy the color schemes and intricate mazes that Mawhorter has come up with - here’s a screenshot of one of the last levels. Check it out if you’re interested - don’t worry, it starts off very easy - and make sure to download Jumpman first.
Who Knew?