407. Drawn: Dark Flight
408. Drawn: Trail Of Shadows
409. Academagia: The Making Of Mages
410. Lux Deluxe
411. Ancient Empires Lux
412. American History Lux
413. Castle Vox
414. Magicka: Complete Edition
415. MANOS: The Hands Of Fate
416. Copy Kitty Turbo Edition
417. Transcendence
418. FarSky
419. Starscape
420. Besiege
421. Red Ace Squadron Pro
422. Out There: Omega Edition
423. Monstrum
424. Super Win the Game
425. Wings Of Saint Nazaire
426. Dreadnought
427. Space Engineers
428. Making History: The Calm And The Storm
429. Making History: The Great War
430. The Mandate
431. The Journey Down
432. Gravity Ghost
433. Amphora
434. A Pixel Story
435. Belladonna
436. White Night
437. ASA: Remastered Edition
438. Fire
439. Westerado: Double Barreled
440. Action Henk
441. Sunset
442. Alum
443. The Silent Age
444. Homesick
445. Quasar: Deluxe Edition
446. The Perils Of Man
447. The Charnel House Trilogy
448. Epanalepsis
449. Tormentum
450. Dominique Pamplemousse
451. The Adventures Of Bertram Fiddle
452. Oblitus
453. Bunker: The Underground Game
454. Duck Game
455. Winged Sakura Mindy's Arc
456. Archibald Adventures
457. Bad Rats: The Rats' Revenge
458. Contraption Maker
459. You Must Build A Boat
460. Rampage Knights
461. BiT Evolution

Probably been mentioned before, but Thomas Was Alone. I love that game!

462. Zenzizenzic

SpeedRunners ! Great game, awesome multiplayer!

463. SpeedRunners

464. Undertale
(97 critic metascore right now, and a lot of praise everywhere).

465. Lost Horizon 2
(published by deep silver, though maybe not really indie. But mighty no.9 and this war of mine too, and are considered indie)

466. Jotun
(gorgeous viking kickstarted action adventure)

467. The Beginner's Guide
(new game by Davey Wreden, the creator of The Stanley Parable. Very short in both playtime and gameplay, but allegedly interesting and with good metascore).

468. Knee Deep
469. Blues And Bullets
470. Albino Lullaby
(three episodic games intesting for different reasons. Knee Deep has great theatrical graphics and orwellian storyline. Blues And Bullets is a beautiful noir c&c offering. And Albion Lullaby is more a weird first person game, more original than the usual.

471. Dead In Bermuda
(Fun and crazy survival management game)

472. Party Hard
(Your neighbours are partying loud, preventing you from sleeping. What can you do? Kill them all, obviously)

473. Volume
(New Mike Bithell game, of Thomas Was Alone's fame).

474. Beyond Eyes
(Extremely beautiful and smart walking simulator)

475. Skyshines Bedlam
(strategic rogue-like turn-based RPG)

476. Contradiction
(An apparently great FMV adventure game -interactive crime drama-)

477. MISSING. An Interactive Thriller
(A so-so episodic FMV thriller -though only the first episode's out-)

Whoa, that list is gonna need a cleanup, a lot of those games have been released since!
Edit: Okay, it's more like, ten games. :-P

And another entry:
478. Slain!
The developer wants to bring the game to GOG:
https://twitter.com/SlainWBG/status/649311036600922112

If you aks the developers, why their games ar not on gog.com, you can often hear: "we would like to sell our game on GOG, but GOG don't want our game"

Jesus Barry. Longest thing I ever saw.

479. Balrum

About This Game
Balrum is an old-school, hybrid turn-based, open world indie RPG with deep tactical combat. Explore a huge living fantasy world with dozens of side quests next to an epic main quest. In addition to traditional RPG features Balrum has deep crafting which allows the player to craft their own custom items. Balrum also features farming your own crops, building your home, and survival mechanics complemented by the game's main features. In Balrum you will have a faithful animal companion as your pet. Your pet is fully controllable and adds greatly to the complexity of the combat.

The player takes control of a young man whose peaceful life is suddenly interrupted by events which will change his life forever.

balconyteam.com

Because I didn't see it : CLOUDBUILT!

http://www.cloudbuiltgame.com/

If you love speed run games, this is a must play.

This thread was already buried.
There was a new one taking its place:
What are the best indie games missing from the GOG catalog? [2016 Edition]