1. Fallout 1 (with HD patch)
2. Fallout 2 (with HD patch)
3. Gothic 1 (widescreen and texture mods applied)
4. Gothic 2
5. Planescape: Torment (with HD patch)
6. Fallout 3 (with a lot of gameplay fixing mods)
7. Unreal Tournament 2k4
8. Freespace 2 (Open with FS1 missions and MediaVP)
9. Vampire - The Masquerade: Bloodlines (with community patch and widescreen hack)
10. Heroes of Might and Magic 3 - Complete (with HD patch)

Those are brilliant games to play over and over again.
You really don't need much else.

1. Fallout 2
2. Heroes 3
3. Master of Orion 2
4. Arcanum
5. New Vegas
6. Age of Empires 2
7. KotoR 2
8. Alpha Centauri
9. Civ
10. Mass Effect 1 and only Mass Effect 1

Honorable Mentions: Deus Ex, Deus Ex: HR, Missionforce: Cyberstorm, Mech Commander, Wing Commander: Privateer, Shadowrun Dragonfall, FTL, Shogun 1 and Medieval 1. Oh and the original Colonization.

I think that covers the spectrum of my tastes in must have essential games.
Edit: Crap, forgot Bloodlines. >.<

Hmm. this was quite a difficult list to narrow it down to however here would be the 10 i would save.

1. Civilization 5
- One of my favorite modern day strats and is a definite game on the list.
2. Sonic 3 & Knuckles
- A classic game that i have spent meany happy hours playing/ stuck on that dam circus stage :P again definite game for the list
3. Freedom Planet
- this game is full of nostalgia for me with the tight platforming and visuals that resemble the Sega mega drive era.
4. Beat Hazard
- A nice game to chill out with your own music, (assuming that survives as well).
5. Sims 2
- This was a difficult one choosing between sims 1 & 2 however i went for 2 in the end as there is a lot more customization in sims 2 than what there is in sims 1.
6. A.i War Fleet command
- Its one of those games that seems simple enought to understand but then once you start unpicking the mechanics the complexity of the game skyrockets. especially when you throw dlc into the mix. if you have played the game you will understand.
7. Age of Empires 2
- This is another strat that i have sunk a lot of time into and still to this day still occasionally enjoy. in the list for nostalgia.
8. Pokemon Emerald
- The thing that sells this to me over the newer games is the battle frontier is massive in this game. particular favorite is the battle factory.
9. Final Fantasy 7
- First and only final fantasy game played and i have still to finish that game, though this was mostly due to accidentally reformatting the memory card and never getting round to finishing the game.
10. Terraira
- The reason i went for terraria over minecraft is that without mods, terraria is a much more fleshed out game than minecraft. (if mods were included however i dont know which way i would sway with this one)

Honorable mentions.

* Unreal - another game that i love playing however

* Rayman 1,2&3 - the rayman franchise also holds nostalgia for me however i have played the games that are on the list alot more than what i have done for any of the individual rayman games.

* Sims 1 - only piped out of the list due to the scope of sims 2 customisation, sims 1 is still able to stand on its own.

1. Forgotten Realms Unlimited Adventures
2. Neverwinter Nights
3. Neverwinter Nights 2
4. Fight the Dragon
5. Shadowrun: Dragonfall DC
6. Divinity: Original Sin
7. Legend of Grimrock
8. Tomb Raider Chronicles
9. Portal 2 or Half-Life 2
10. maybe Dragon Age: Origins (quite a bit of custom content, not so much fun) or Driftmoon (fun game, next to no custom content)

That's provided I'd still have access to the internet and the websites of the according modding communities, as well as a lot of time on my hands. ;)

Well, that is quite certainly an interesting choice

Let's limit the choice to GOG games that I played...

Terraria
X2: Silent Threat (probably X3 once I've played it)
Flatout 2 (need a racing game)
Jedi Knight: Jedi Academy (need a shooter)
Rogue Legacy or Valdis Story (need an action platformer)
FTL
Master of Orion 2
Lovers In a Dangerous Spacetime (need a good hotseat game)
Don't Starve
Normally, I'd reserve the last spot for some turn-based tactical game with solid replayability (ex: X-Com), but having played none on GOG so far, maybe Freespace 2 instead.

Overall, I'd stay clear or RPGs and Adventure games, not because I don't like them, but because they have low replay value and if you'll limit yourself to 10 games, you want them to have a very high replay value.

This list would probably change as I play more games :P.

Picked from my GOG catalogue:

1. Alpha Centauri
2. Daggerfall
3. Master of Orion 2
4. Unreal Tournament (Original)
5. Age of Wonders
6. Eador Genesis
7. Battle Realms
8. Darklands
9. Sacrifice
10. Betrayal at Krondor

So what about me....

1. Minecraft
=> Been playing this game since 2010, and I still can't let go of it, I even own the multiple versions of it (PC Java, Windows 10 Edition and Pocket Edition for Android)
2. Duke Nukem 3D
=> I also can't let go of the best shooter one can play
3. Final Fantasy V
=> Its the best title in the Final Fantasy franchise alongside...
4. Final Fantasy VII
=> ...another best title in the Final Fantasy franchise!
5. Sonic Adventure DX
=> Probably the best title in the Sonic series.
6. Grand Theft Auto San Andreas
=> The game is just too vast.
7. Minesweeper
=> I love hate the game!
8. Super Mario Bros
=> I need a break from Sonic sometimes you know?
9. International Snooker
=> Sometimes, a snooker game is useful.
10. A SimCity game
=> I need to be a mayor sometimes...

That's like asking which of your children do you love the most. What is this, Sophie's Choice?

- Final Fantasy 1,4,5,6,7,8,9,10
- Persona 4
- Chrono Cross

aw already done? I got so much more to save.

Gog's Twitch mod
not one of the favourite games on GoG

oO

All games as GotY/Complete/Ultimate/whatever versions:

Borderlands 2
A fast paced, crazy shooter. And quite challenging if you're playing it as a singleplayer (I never touched the multiplayer of this game!). Every class needs a different play style. Hundreds of hours of fun.

Diablo II
I don't think I'll have to explain why I'd save this game. It's one of the very few games that's accepted by most gamers as one of the best games of all times.

Final Fantasy VII
Because it was my first "HOLY ****" game on the PS1. It's from an era where gaming became my main hobby - and this game was one of the reasons for this! There are Final Fantasies with better stories and better gameplay (gameplay wise I'd love to save FFX with it's monster farm - story and world were way better in IX and XII), but... FFVII just has this special place in my heart.

GTA V
I liked it. The story was fun, the gameplay felt great, you have lots of possibilities... It was a bit too easy (I'd say it was pretty hard to FAIL a mission), but I really liked this game.

Master of Orion II
Because of the soundtrack. And because it's still one of the best 4X games ;P

S.T.A.L.K.E.R.: Call of Pripyat
It's the perfect mix of survival, shooting and scariness. It's a dangerous world where you have to watch your back all the time and where you have to think before you start to shoot. Sometimes you get screwed by the zone and it's dangers, but some other times these dangers save your ass. One of the most immersive games I've ever played.

Vandal Hearts II
Another game from the PS1 era that influenced me heavily. It's the reason why I love turn based, tactical combat. And I think it's still looking great: , [url=http://whosnerd.com/wp-content/uploads/2012/02/igorqueiroz_vandal_hearts_3_02.17.02.jpg]2, , [url=http://lpix.org/images/Azure_Horizon/f420099a5e68ceae437e7a9c8153586e/PSD3D241.jpg]4 I'd love to be able to play it again :(

Wing Commander IV
This game is my favorite space sim EVER. I love the ships, I love the story, I love the flying. I think I can't live without this game.

X3: Terran Conflict
I've dumped more than a thousand hours (!!!) in this game already and still start new games to do new things (there are a lot of mods out there). And it's simply a satisfying feeling to jump into a Xenon sector with a carrier full of fighters, two destroyers and a handful of escort frigates to destroy the Xenon ships in one deadly strike - keeping a frigatte loaded with ion canons in another sector, ready to jump in togehter with a M7M, waiting to send out your marines to board this last Xenon Q :D

Zelda II: The Adventure of Link
Because I'll never forget how I felt when I first beat this game. I found it pretty hard when I played it as a little boy. Especially those stupid knights with their shields... They knew where you're going to attack them even before you knew it >:( I still hate them! But I loved the side scrolling levels and the battle and magic system (and leveling up attributes with EXP!).

I'd really love to save TES: Oblivion too (most people who love classic games hate it, but it's my favortie TES game because of some of the sidequests, like Thieve's Guild or the Dark Brotherhood), but I can't find a game that I'd kick out of my list for Oblivion. GTA V was a candidate, but... No, I wouldn't want to kick it out for Oblivion :/

Because I trust my gog library to never disappear =o

but if I have to save 10 games from my gog library...

Then it would be Recettear, Divinity Original Sin, Pillars of Eternity, Witcher 1, 2 and 3, Age of Wonders 1 and 3, VVVVVV and Serious Sam

Tough question. Is there multi-player available? I'll assume it is.

1. Expeditions Conquistador
2. StarCraft 2
3. Rogue Squadron
4. Baldur's Gate 2
5. King of Dragon Pass
6. Civilization 4
7. Age of Wonders 3
8. Majesty
9. Master of Orion 2
10. Imperialism

Wow! This was harder than I thought! The game are in particular order as I had to replace some games when I realized a genre was missing. For example, taking out StarCraft for Expeditions Conquistador. There were still a lot of great games I had to leave out! Some games I loved, like To The Moon, I had to leave out because it doesn't have great replayability. I love Mark of the Ninja too, but worry about replayability for the same reason.

Fun exercise!

*edit* I left out FTL... Where do I put it!

A little dark there with the Sophie's Choice reference. Just choose 10 of what I like to call "sacred games". And if you cannot chose, then have them compete in a tournament of MORTAL KOMBAT!

https://youtu.be/EAwWPadFsOA