Reading Mausritter, an RPG where you are adventuring mice. The author cites Into the Odd and Knave as system inspirations, Mothership for layout, Mouse Guard and Mice & Mystics for theme & tone.

It's super-cute and packs a lot of tools into 24 pages https://losing-games.itch.io/mausritter 

The inside-front-cover is a table of gear for sale in pips, the "standard currency of the mouse kingdom".

Don't worry, starting characters have their equipment generated for them in the style of Into the Odd, so you can get straight to the adventure.

The equipment for sale is your standard D&Dish nonmagical gear and dungeoncrawling tools, rethemed for mouse-sized characters. Notably the adventuring gear is divided into mouse-made and human-made (latter only available in mouse settlements near where humans live)

Chargen is simple and mostly random. The author has provided an online generator too:
https://losing.games/mausritter/mouse/

Stats are Str, Dex, Will. Each is the best 2 of 3d6.

The scores this produces look like this

To succeed on a task where the outcome is in doubt, you roll 1d20 *equal or below* the related score. Advantage & disadvantage can apply.

Yes, an average mouse will fail 55% of rolls, and the most gifted mouse will still fail 40% of rolls.

Make plans that don't require rolls!

Anyway you can swap two of your stats, so you're allowed some customisation.

You then roll on tables for:
* Birthsign, which determines your disposition. Each has two qualities, softly divided into virtue and vice. e.g. Nurturing/Worrying.
* Coat Appearance
* Physical Detail.

You then roll 1d6 for starting HP and starting Pips. HP is your capacity to avoid harm, like in Into the Odd, once HP is depleted, damage goes onto one of your stats (typically STR). So an HP of 1 is less disastrous than in, say, B/X, but still scary.

You then cross reference your HP and Pips against a table to determine your Background, with gives you starting equipment. Like ItO, worse HP & pip rolls mean you start with better stuff. If you have bad/mediocre stats, you then *roll* on the table as well.

e.g. a mouse whose highest stat is 8, and who starts with 1 HP and 2 Pips, was a kitchen forager before becoming an adventurer. They start with a shield & jerkin, cookpots, plus what all mice start with: torches, rations, and weapon of your choice...

... Because their highest stat is 8, I roll again on the background table and choose *one* of the items it gives me. I roll (1, 4), and start with a healing spell from the Hedge witch background. Maybe I nicked it off them?

Unlike Into the Odd, the worse equipment given to characters who roll better doesn't include any negative entries like "debt" or "a missing arm". Just less obviously useful stuff like a felt hat.

Anyway I'm a huge fan of this kind of character generation. The birthsign, appearance & physical detail tables mostly don't give any mechanical or in-fiction advantages, so you can just let players choose instead of roll.

You have no class features, just the stuff you carry. Each character has an inventory with:
* a main paw and off-paw slot
* two body slots. Worn armour goes here, or other things you want readily at-hand.
* six slots in your pack. Items here take time to retrieve.

You get these cute item cards to fill in your slots.

Geometry is important! e.g. light and heavy armour provide the same defense, but light armour takes up your off-paw slot and one body slot, while heavy armour takes both your body slots.

(it's unclear whether you can rotate cards that are in your pack)

Importantly, conditions you might receive, like "Hungry" or "Frightened", are also represented as cards that take up a slot!

You can carry more stuff than you have slots, but this leaves you encumbered.

Also note that various item cards have three little dots to mark usage. This is a game that prioritises item bookkeeping instead of class features, but it makes that bookkeeping as easy as possible.

(ammunition is tested after each fight. 50% chance of marking a dot)

you can store stuff like extra pips and unwanted gear in a mouse bank at a settlement. Mice in settlements also generally deal in barter and IOUs rather than using pips for every transaction.

Then we get to the How to Play section. A quick summary of old-school player principles, then the core mechanics. Again, rolling dice is dangerous -- scheme with other mice to make plans that avoid rolling.

* Saving throws (i.e. any task where outcome is in doubt) are d20-roll-equal-or-below, as mentioned before. For opposed rolls, each side rolls d20, the lowest successful roll wins.

* Attacks always hit. Roll weapon damage, subtract from the target's HP, then from their Str stat.

* Damage is a die roll determined by weapon type. No ability score modifiers. This ranges from d6 for small weapons to d10 for heavy weapons.

* Armour (whether light or heavy) subtracts 1 damage.

* since there's no to-hit roll, advantage/disadvantage doesn't apply here. Attacks that are impaired (e.g. firing into cover) always deal 1d4 damage, attacks that are enhanced (e.g. a backstab) always deal 1d12.

(you could houserule that the attacker instead rolls their normal damage die twice, taking the best/worst. I'm not sure why the author decided not to do that)

* If your Str score is reduced to 0, you die immediately.

* Otherwise, if an attack deals Str damage to you, you then make an Str save (using your now-reduced score). If you fail, you are knocked out and take the Injured condition. If you aren't tended to in 6 turns, you die.

Note "6 turns" here means the old-school "dungeon turn" of ~10 minutes. So if you take a wound, e.g. while exploring ahead on your own, you can survive an hour without treatment.

A short rest (one turn or 10 minutes) restores 1d6+1 HP. A long rest (one watch or 6 hours) restores all HP, or 1d6 to a damaged stat if your HP is already full. A week's rest in safety clears all damage and most conditions.

Some simple hexcrawl and foraging rules follow

You level-up by:
* bringing treasure back to the safety of mouse settlements. 1 pip = 1 XP.
* spending pips on selfless improvements for the community. 10 pips = 1 XP. A nice touch!

XP thresholds are 1000, 3000, 6000, then +5000 for each level thereafter.

Each level-up your stats and HP may improve.

Stats: for each stat, roll d20. If it's *greater than* the stat, increase by 1.

HP: roll d6 equal to your new level (maximum of 4d6). If the result > current max HP, it becomes your new max HP. Otherwise, increase max HP by 1.

You also get a resource called Grit, which is basically virtual inventory slots you place conditions in before they start taking up your real inventory slots. It maxes out at 3. That is, advancement plateaus after level 5 or so, depending on how bad your starting stat rolls were.

Spells!
Like in Knave, each spell is a separate item taking a slot. Spells (beyond any you start with) must generally be recovered as treasure or stolen. Though they can be sold, so presumably you can sometimes buy them.

Spells have three usage dots.

When you cast a spell, you choose how much power to cast it with, up to the number of unmarked dots.

Roll that many d6 to determine effect. Higher rolls are a stronger effect, but will also cause dots to be marked, or cause you to take Will damage.

Each spell has a unique ritual that must be conducted to coax the spirit back into the item and clear usage dots. e.g. Ghost Beetle (a spell similar to Tenser's Floating Disc) is recharged by burying the spell tablet in a beetle graveyard for three nights.

This is a really cool alternative to the level-less Vancian system that Knave presents for its spells, particularly if you like magic to carry some risk.

The GMing section has standard old-school principles: let players find their own adventure, present the world honestly, telegraph danger, be an impartial arbiter, reward bravery.

Also make the world seem huge -- they're mice!

Various tools, like X-in-6 rolls for luck-based things outside the characters' control, various possible consequences for failing a save (besides damage), weather tables, random encounter rolls, reaction rolls, all the usual old-school stuff.

Creatures. Each creature has stats similar to player characters, probably a special power or two. Each has a unique 1d6 table, e.g. NPC mice have Rival Mouse Adventurers, Ghosts have Ghostly Powers, Faeries have a list of Agendas. A really cool idea here.

Then there's instructions for creating a hexcrawl (with an example so you can start playing immediately).

The rest of the book is a bunch of random tables for hex contents, landmarks, mouse settlement details, adventure sites and their denizens, adventure seeds, and NPC mice.

Finally a quick reference sheet summarising basic mechanics and the rules for resting and spellcasting.

an example Adventure Site roll:

Construction: Noblemouse's country manor
Ruination: Disease
Inhabitants: Rat King's warband
...Searching For/Protecting: The last scraps in a picked-over ruin
Secret: Monolith humming with arcane energy

An example Mouse Settlement roll:

Name: Figdale
Size: Village (150-300 mice)
Inhabitants: Spend their days lazing by a stream
Notable Feature: Ornate gate guarded by statues
Event: Wizard tower arrives on tortoise-back (!)

An example NPC mouse:

Name: Sorrel Grant
Position: Common
Birthsign: Mother (nurturing/worrying)
Appearance: bent-twig walking stick
Quirk: quick, erratic speech
Wants: Power

An example Adventure Seed:

a Mouse Matriach's home is under attack, the antagonist is very drunk.

summary:

* a great melding of Into the Odd and Knave with ideas borrowed from other authors/bloggers
* The illustrations throughout are adorable, print-friendly and set tone well
* Monsters and GM tables are dense with setting detail

* if you're at all familiar with OSR games, you already know how to run this
* if you're not, it has a good summary of GMing principles, avoids the peculiarities of retroclones, and has straightforward, classless player-facing rules.

Like all good OSR games, it's eminently hackable, reskinnable, and adaptable.

Unlike a typical B/X clone, characters are a bit more resilient to damage at 1st level, though attacks always hit. Spellcasters will have more than one spell slot available.

It's a steal at $3.

Now, some things that may mean this game isn't your cup of tea. Or possibly that it's *more* your cup of tea?

* there's no metanarrative currency or any other way to ameliorate a bad roll.

* there's no mechanics, or GM advice, around testing the characters' beliefs, like there is in Mouse Guard. Similarly, there's no rule (beyond XP for community improvement) that disincentivises being a murderhobo. That's left to in-fiction stuff like villages ostracising you.

* The creatures of the setting have baked-in morality. If you're not a fan of games that cast all rats as wicked brutes, or all cats as cruel and overweening, you'll get less use out of the GM-facing stuff.

* If you want character abilities outside of what stuff they carry, or hate any form of item management (even the easy visual version this presents) then I don't know how you made it this far??????

* If you want a ruleset that rewards players for making the "badass" play like charging in to fight the scorpion one-on-one, uhhh, this isn't the game for you. The scorpion will snip their head off...

...this is the ruleset where you try to negotiate with the scorpion (from a safe distance!), avoid it altogether, or lure it under a cinderblock you've positioned atop a ditch.

* The dying rules may not be to your taste. Now this is easily changed -- just temporarily incapacitate mice, have them captured, or forced to retire from adventuring instead of character death.

* Finally this game requires a full set of polyhedral dice. You *could* hack it so that all player-facing stuff is d20 & d6 only (the other dice only get used for weapon damage)

That said, this game is great, and is one of the games I will now point to as an example of what the OSR is capable of besides the somewhat stereotypical "body-horror lair of the tiddy-hydra" or "here's another take on Keep on the Borderlands"