THAW is an old-school TTRPG system based on the sleepover favorite folk game MASH. MASH, if you haven't played it, is a game about prioritizing picks from different lists---good car, mediocre husband, bad house, that sort of thing.
I'd describe this genre of thing as sleepOSRver.
THAW's PDF is 36 pages, very cleanly laid out, and it has the broad vibe of an activity book.
Character-creation-wise, when you play THAW you play MASH. You write down a bunch of possible traits for your character, than eliminate them one at a time until you're left with a pick from each list. It's not exactly random, but it's complex enough that it'll generate characters that feel both familiar and unexpected.
Mechanics-wise, THAW has some real weight. Each MASH pick gives you passive benefits and different ways to break the game's rules, and these can get pretty creative: pre-mapped dungeons, extra gold for bribes, walkie talkies between dungeon and town.
For rolls, THAW has you pre-generate numbers and then pick from them when faced with checks. When you run through your numbers, you gain a level and then generate a new set.
This approach kind of encourages the GM to slow play the game, making it so that checks only occur when it's really, REALLY important and each check has massive narrative weight. I think for that reason THAW might work especially well for 1 GM, 1 player setups---although you could also cut the other way and play THAW really fast and loose, churning through rolls and advancing all the way to level 10 in a night.
And with all of that said, THAW is a *very* GM friendly game. Test DCs, dungeon maps, these are all generated via the same MASH system, and the book gives good and clear and personable guidance throughout. A total newbie could pick up THAW and be fine. And a veteran could probably use it to slap together dungeons for this or other systems at extremely high speed.
Overall, THAW is a gem. It channels the creativity, improv, and speed of play of OSR into a new and refreshing format. It's a sleepover game. It's DnD. It's a dang good time.
Minor Issues:
-Damage numbers are pretty small, so +d4 HP on a level might make characters pretty unkillable around level 5. This assumption is based on me eyeballing it, so grain of salt, I might be mental-mathing it wrong. A class-based HP cap could change this, with the surplus HP floating into gold points instead.