Non-GURPS

13th Age (d20; fantasy)
Advanced Fighting Fantasy (2d6; fantasy)
Adventures in Middle-Earth (D&D 5E SRD; fantasy)
Ars Magica
Baker Street (d6 dice pool; Victorian age)
BattleTech (Mechwarrior: Destiny, Cue System with 2d6; science fiction/mecha)
Blue Rose 2E (True20; fantasy)
Cyberpunk (d10; science fiction/cyberpunk)
DC Comics RPGs (DC Heroes: MEGS, DC Universe: WEG d6, DC Adventures: M&M d20; superhero)
Delta Green
Doctor Who RPGs (Time Lord: d6-d6, C7 Doctor Who: 2d6 Unisystem variant; science fiction/time travel)
Dragon Warriors (d20; fantasy)
Dungeon Crawl Classics (modified d20 SRD; fantasy)
Dusk City Outlaws (custom dice or d8/d10; fantasy heists)
Dying Earth
Elephant and Macaw Banner
Esoterrorists, The
Everyday Heroes
Fate
Fate of the Norns
Flash Gordon
Forged in the Dark
Gamma World
Girl Power
Godbound
HERO System
Household RPG
ICONS
Jovian Chronicles
Judge Dredd
Lone Wolf
Mercenaries, Spies and Private Eyes
Metamorphosis Alpha
Mistborn Adventure Game
Mörg Borg
Mutant Crawl Classics
Mutants & Masterminds
Mythras
Night's Black Agents
Numenera
Paranoia
Pathfinder
RuneQuest
Shadowrun
Shield Maidens
Space: 1889
Star Frontiers
Starfinder
Starship Troopers
Symbaroum
Talislanta
Trail of Cthulhu
Trophy
Tunnels & Trolls
Twilight: 2000
Valiant Universe
Vampire the Masquerade 5E
Victorious
Warhammer Age of Sigmar
Warhammer Fantasy Roleplay
Warhammer 40k
Yellow King

2d20 System (Modiphius)

Conan: Adventures in an Age Undreamed Of (in Conan)
Dune: Adventures in the Imperium
John Carter of Mars
Mutant Chronicles 3E
Star Trek Adventures (in Star Fleet Universe)

Old School Renaissance (OSR)

Dungeons & Dragons (D&D Basic, D&D Advanced)

Retro-Clones

Basic Fantasy (D&D B/X)
Labyrinth Lord (D&D B/X, AD&D 1E)
Old-School Essentials (D&D B/X)
Swords & Wizardry (OD&D with AD&D 1E inspired-extras)

D&D-Likes

Hyperborea (B/X and AD&D 1E, leaning towards latter; fantasy)
Mazes & Minotaurs (inspired by D&D, Tunnels & Trolls and Dragon Warriors)
Sine Nomine Publishing (RPGs that use Basic D&D inspired rules)

Powered by the Apocalypse/Apocalypse Engine

Year Zero Engine (Free League Publishing)

RPG Accessories
RPG Life
RPG Small-Shots
RPG Supplements