It's a grey area, unfortunately. The thing is that the main purpose of this list was to find out which games on GOG have internal achievement systems, comparable to, but indipendent from, Steam/Galaxy/XBLive achievements. Eschalon has optional challenges, but I don't know if they could count as achievements as we know them, The Saboteur had something similar (playstyle-related challenges which give you special perks when fulfilled). There are borderline cases like these, usually with older games.

King's Bounty: Warriors of the North

Red Faction: Guerrilla Re-Mars-tered

I don't know the game in question at all so I cannot say anything about it. My reply was focused on the fact why games like Indiana Jones are not on the list anymore and your statement that it is off the list because the achievements are "pretty weird". Imo the question to ask is simply "are these optional challenges not necessary to finish the game?". If you say "Echalon has optional challenges" I'd say it should be on the list if there is any kind of badge available ingame when you did this. But again - I don't know the game so won't lean myself too much out of the window here :)

Maybe you're right, I'll add it to the list (with a little disclaimer in the description) :)
Added both, thank you!


OT: does anyone know of a way to better manage GOGmixes? It's a pain to try to order the games alphabetically

Someone with javascript knowledge could surely come up with a userscript to make GOGmixes manageable, but lacking that I've found a sort of "hack" for quickly sorting elements up the list. All you need is an Android device. The trick lies in getting the game you want to "boost upwards" nearly at the top of the screen, but not quite: you still need to see the bottom-half part of the previous game thumbnail. Then, if you tap the "Up" button, the two games will switch places as expected, but the game you want to move upwards will remain in the same place relative to the window. So you can keep on tapping the "Up" button in rapid succession until you get that game to the desired position.

In case my explanation was too confusing, please check the attached screenshot. In that case, imagine you want to move The Swindle upwards. If you tap its "Up" button, The Swindle will not move, but now the previous game (Subject 13) will appear right below The Swindle, right at the spot previously occupied by The Witcher Adventure Game. Rinse and repeat. :)

I'll try this, thanks!

Sorry for the late answer, thanks! (The game is on my backlog btw, I should play it at some point)

Ps: looks like the GOGmixes are bugged, I'll update mine later. In the meantime, the game is already on the list.

You should. Even though the gameplay is pretty generic the narrative, artstyle and music is amazing. Had a lot of fun with it.

Reus has ingame achievements regarding to this YouTube Let' Play:
https://youtu.be/giDFdSjvMwo

You can notice this in game options called "unlocks", "achievements" or by viewing the video at minute 1:15.
I do not own the game nor am i related to the content creator...but because it's on todays daily deal i was curious about the gameplay and stumpled upon this.

Cheers

Interesting, added to the list!

I still can't update the mix because GOGMixes are still broken (it's been almost a month and it's getting ridiculous)

Hybrid Wars has ingame achievements as well.

Added!

Cinders (it was a couple of days ago a daily deal) seems to have so called "rewards" (you can notice this option at the store, screenshot section). I do not own the game, so i was only able to find screenshots & also youtube/wiki explanations which kind of proofed that there is a trophy system. Maybe someone who owns the game can 100% confirm.
Speaking of in game // galaxy achievements - Grim Dawn has in game Achievements as well (like Into the Breach...which also made it to this very list). I can confirm, because i played it a lo(o)t. ;-)