It's May Day today, and in the spirit of the day, here's a brand new expanded version of Into the Depths for free! (Link is to a downloadable pdf on Google Drive) (2018-05-11 edit: I've now changed the link to the newest version incorporating errata)
Into the Depths is my "core" ruleset for playing old school fantasy adventure games, as conveyed in four densely written pages. I've been running and playing in games using it for a little over two years now, and this is the first major revision since 2016, with the revisions based on my experiences playtesting it over that period.
Into the Depths might be the game for you if you're looking for a low magic rules-set that mechanically encourages dynamic fights and chases and that has a stellar gear list that serves in place of a power or magic system in most instances.
New material includes:
More gear options
More secret fighting techniques to learn
A magic system
An updated levelling rubric
The ability to be bad at things
Rule sections rewritten for clarity and ease of use
Numerous tweaks to the mathematical structures
One last change is that I'm opening up the copyleft on it further. Previous versions of Into the Depths were available under a noncommercial Creative Commons license. This newest revision is now available for commercial use (with attribution) for anyone who would like to publish and sell works using it as the ruleset.