Mods are starting to come out now, there being four that I'm aware of.


UI Mod

Adds options to change the UI.

Lightbringer

Swaps your regular attack with ranged lances of light. Adds new charms that work with your new ranged attack and a charm notch.

Glass Soul

For when Steel Soul is not enough. One hit and you die, but your attack does more damage and you get an extra charm notch. Works with both the regular mode and Steel Soul mode.

Cut Content Mod

Adds cut content. It doesn't look like it currently adds anything beyond extra rooms that were cut during development.

Blackmoth
Dash does damage and replaces nail as main attack. Upgrades alter it further.

110%
Adds further requirements for full completion to make it more difficult.

MISC mods

A mod that lets you shrink or grow yourself, an extra boss and a co-op mod of sorts.

for those lake me, that really want to explore all the world but are totally stumped by a boss you couldn't beat...

an invulnerability mod to activate just to get rid of the aforementioned boss, then disable again or you loose all the joy of playing the game

https://www.moddb.com/games/hollow-knight/downloads/hollow-knight-invulnerability-1432

ModInstaller

https://www.moddb.com/mods/modinstaller/downloads/modinstaller

https://drive.google.com/drive/folders/0B_b9PFqx_PR9Um9MeFZMV21oWGs

Is there one that lets you quit without saving or one that just lowers the prices of early items like the markers and compass?

One that makes the compass and swarm charms not take up any slots would also be cool.