In my opinion, the best of the rules-lite horror RPGs. A very clever and fun system. I create the PCs with 2d20+30 to make them more distinct. Here is a quick conversion guide I hacked to convert monsters and beasts from the 7th edition of the Most popular cosmic horror game:

Action = DEX-10 Health = (HP*2) + 10 Muscle = STR/2 Notice= (Action + Reason) / 2 Reason = INT If 0 = 10 Spirit = POW-10

*If any calculation goes over 100, adjust to 85 or 95 (for most powerful beings or deieties) If any calculation goes negative, adjust to 10

Damage dice:

Animals will usually use d6 (with d4 for the weakest like a bat) Monsters will usually use d8 (with d6 for the weakest like a zombie) Gods 2d8 (2d6 for lesser gods) plus some special effect.

One of the best single book RPGs ever compiled. A toolbox to let your imagination loose—create characters with life stories, worlds, subsectors, starships... Alright, maybe the task resolution or the combat are not streamlined, but these are easy fixes. It was the concept that was, and still is, revolutionary: procedural creation, fractal universes, the stars our destination.