Tacticians Of Ahm is a retro tactics TTRPG.
The PDF is 8 pages, with an aesthetic that makes it feel a bit like a NES game manual.
Lorewise, you play as high fantasy warriors and mages in a realm that has mostly known peace, but is now headed into a Rough Patch.
Despite the game's brevity, there's some nice meat to the lore (as well as some hints that maybe this is canonically a universe inside of a game, with glitches creeping in). It feels easy to anticipate the game's tone and make characters and GMing decisions that gel with its setting.
Gameplay-wise, Tacticians is a micro tactics game in the style of Into The Breach or the original Fire Emblem. Combat plays on a grid. Characters have a few but very meaningful abilities. Attacks always hit. Progression is tight.
There *is* out of combat adventuring, but it's stripped down. Likewise, without modifying the rules, combat is pretty simple and direct too. However, by cutting right to the core of what the game is about, Tacticians makes itself into a fantastic one-shot or convention game---for a long campaign, you might need to either lean on your GMing skills or expand it with some homebrew.
Overall, this is a gem. If you liked dnd 4e, or if you enjoy retro tactics games, or if you're just looking for a very bite-sized, very combat focused TTRPG, you should pick this up. It's a great game to have in your library, both as a design reference, material for a mini-campaign, and a break-glass-in-case-of substitution for heftier titles.