Deleted

• Natural selection 2
• Borderlands 2
• Skyrim
• Fallout New Vegas
• Dishonored

1. Starbound
2. Fallout 3/NV
3. Borderlands 2
4. Towerfall Ascension
5. Tabletop Simulator

Already got a multiple of my money in playing hours out of starbound, and it was not even fully released yet

Assassins Creed 1 (i own the rest on uplay :P)
Brothers - A Tale of Two Sons
Ryse: Son of Rome
Rocket League
Portal 2
Orcs Must Die 2
Dirt Rally
Bloons TD5
Payday 2
damn this list got too long:(

Europa Universalis IV
Crusader Kings II
Hearts of Iron III
Victoria II
----->Paradox Grand Strategy Collection
and probably CS:GO.

Counter Strike Global Offensive
Amnesia The Dark Descent
Bioshock Infinite
Skyrim
Garry's Mod

CS:GO
CS:GO
CS:GO
CS:GO
and CS:GO

The Witcher 1,2 & 3
Civilization V
Total War Series
Dishonored
Tomb Raider (2013)

(and many more, like: Prison Architect, Car Mechanic Simulator 2015, KOTOR 1 and 2, Eurotruck Simulator 2, Max Payne 3, Xcom: Enemy Uknown, Bulletstorm, Lego Series, Sleeping Dogs, AC: Black Flag, etc.) By the way Not everything on steam

Bust a groove.
Demolition racer.
Legend of mana.
Counter strike./Bomberman world
Team buddies

Skyrim
Borderlands 2
Fable Anniversary
Killing Floor 2
Dark souls

Borderlands 2
Skyrim
The Witcher 3
Left 4 Dead 2
Maybe Batman Arkham City.

Probably those! Not my favourite ones but if I had to buy only 5 that would be my choices considering the amount of hours you are supposed to play with those!

Mass Effect Trilogy
Skyrim
Max Payne Trilogy
Metro 2033 pack
Dishonored

(Technically, list above consists of more games... but since I bought it as a pack each, it counts as "one buy again")
I strongly recommend the ME trilogy for those unfortunate, poor souls that have not yet experience the great story of Commander Shepard.

Hard choice. At the moment I would say:
Broforce
The Binding of Isaac
Distance
Audiosurf 2
Civ 5

Mass effect & mass effect 2, endless space, deus ex hr, portal 2

Skyrim , Dying Light , Metro 2033 , CS Complete , l4d2

Torchlight 2
Bastion
Trine 2
Half-life 2
Fallout: New Vegas

Rome Total War, Total War Rome 2, Medieval 2 Total War, Crusader Kings 2 and Euro Truck Simulator 2 (since I'm currently really enjoying that, it just makes me relax for a moment and forget about the world around me (just like the music I listen to))

Evil Genius
Skyrim
Ark - Survival Evolved
Warhammer 40k - Dawn of War
Fallout 3

I actually have bought four of these 2x... Retail boxes on first release and then Steam versions.

Simcity4
Resident Evil HD
Baldur's Gate series
Prison Architect
Dark Soul

Tomb Raider 2013
Mount and Blade: Warband
Resident Evil: Revelations
Remember Me
Ukrainian Ninja

I can't believe Antichamber wasn't mentioned yet...

Antichamber
FTL: Faster than Light
The Walking Dead (Telltale Series)
Bioshock Infinite/Borderlands Series/Fallout 3+
Monaco

1) (and this isn't close) Skyrim Legendary Ed I'm STILL playing it all modded up.
2) 7 Days to Die
3) Talisman Digital Ed. (with my DLC)
4) Ticket to Ride complete (I don't have the complete DLC, but if I had to rebuy it I would)
5) Maybe Rise of Flight with the DLC as well... tough call on the 5th one, it's mainly the top 4 I play.

Considering all:

1) Age of Empires (not sure which one)

I can't think any other steam game I return to more than that one. I might say FIFA, but it's not steam =P

cities skyline
life is strange
gta V
just cause 2 (had most my playtime on ps3, but still liked the pc verson a lot)
saints row: gat out of hell

Hmm... That is quite difficult question. One possible list:
Dark Souls or Dark Souls II: Tough cookie. Can't say which of those were better, could be because I bought DS year before the release date of DS II so I didn't have long experience with it. DS II had the looks but both have really enchanting atmosphere and playing style.

Plague Inc. Evolved: one game I can't get enough. I don't have long playtime in steam but I used to play it on my smartphone. Small game but real timesink.

Dragon Age: Origins Ultimate Edition: One of the best 'new' western RPGs imho. It isn't so deep as old Baldur's Gates but it still gave my dose of RPG fun and immersion. Yes, there were the Bioware 'magic' like gay relationships (some abhor them, I know) and some irritating characters but the game was a gem (although the plot was really typical) with fitting soundtrack. Also the dlcs were quite nice if you don't count the feastday pranks and gifts.

XCOM: Enemy Within: I first wrote Dawn of War II but changed it to this. When I was young I used to play the UFO: Enemy Unknown (or "X-COM: UFO Defense" for Americans) day after day, trying to create different challenges when I was bored etc. Althought the Enemy Withing wasn't the same classic and was a bit streamlined it was still very good remake or reimagination of the same situation. Now I'm waiting for XCOM 2, actually preordered it couple of weeks ago.

Skyrim / Fallout New Vegas: New Vegas was really good experience for me, I did like the dlcs a lot, even the funny Old World Blues. Skyrim had the awesome mod library and shouting trolls of the mountains made my day a bit brighter. Yup, I hate them.

Didn't include Left 4 Dead 2 since my friends don't play it anymore... shame really. And Alien Swarm is free so if someone would play it I could still get it ;D

Grim Dawn
DayZ
Starbound
Skyrim
GTA V
:P