which game(s) that was sold on Steam but later removed you regret not having?

Wolfenstein 2009.

And I'm shocked by how many there are who actually want Fable 3. Dear god that game was bland. One button combat (just hit the same button over and over again and you win), quest markers that did not work properly and "social interaction" that made no sense (why exactly do strangers like me more for farting in their face?). It's really one of the most shallow games I've ever played, and while the story had some promise, it did not amount to much during my playtime. Oh, and whoever designed the "menus" must have been drunk, because every time you wanted to access a menu you had go through a loading screen, because the "menus" were actually a "physical" place in the world that you moved to and walked around in..

I have been using Steam for just a year and a half, so I don't know of many games that were on Steam before and removed later.
I was missing Deadpool, but it's back and o sale right now.
Never even heard of Prey, the game almost everyone is talking about.
I have Saw, Mafia II and Family Guy: Back to the Multiverse. They were removed and I would be very sad if I didn't had purchased them before that happened.

I had Dreamkiller on WL for several years, I just couldn't afford it.

Hawx series. They were on my wl but was short on cash when they went on sale.

Prey
Outrun 2006
Cryostasis
Wik and the Fable of Souls

And there's probably more I don't remember right now.

Fable 3

007 Legends
CSI: Hard Evidence
Dragon Age II
King's Quest collection
Outrun 2006: Coast2Coast

007 Blood Stone & Legends
2009's Wolfenstein

Fable 3
Mafia
Prey
Blur
Wolfenstein (2009)

Lesser extent:
Godfather I & II
Risk I & II
Spider-man 1 & 2
007
CSI

My kids all want Avatar. I have it on my account, but my Steam share only works for them if I'm not playing something. They can also only have one at a time using it on Steam share. It's inconvenient to log into their machine and go into offline mode (since I won't let them have my password) every time they want to play it, and since they're kids, they want to go back to playing their games on their account after an hour or so.

Breach, because of the destruction type aspects..

Well I came here to comment Prey, but then I found out Onimusha 3 used to be on steam and that destroyed my day since I loved that game back on the PS2 :(

There is also Dragon Age 2 since I don't use Origin.

Fable 3 (though apparently it was a terrible port.)

wolfenstein 2009 and prey. i love those games. <3

is there any chance for mafia to come back on steam?

Can't think of any that I missed on steam....but one that I would LOVE to see the multiplayer come back to life on is Return to Castle Wolfenstein...
good memories <3

Outrun 2006: Coast to Coast.

Heard HoMM 3 (the original, not HD) was on Steam before. Sadly, I wasn't there yet to snatch it.

Every1 says prey, but you can still buy that 1 on kinguin.

mafia 1, and the godfather

Dragon Age 2
Afterfall insanity
Mafia 1

Stubbs the Zombie, Outrun 2006, Blur, Wolfenstein 2009, Dragon Age II, Darkspore, Mafia 1 (I have it on disc, but you know... gotta collect 'em all) - and of course, two of the greatest gems of all time, Horrid Henry and Stalin vs. Martians

Stubbs the zombie. Got it on Xbox just before it was pulled from the marketplace, but it never worked. Support was useless and may as well have told me to crunch up and gobble my own knob.

Blur looked fun, also Wolfenstein.

NeverWinter Nights 2 is the one release I would love to see back on steam.

Blur, Mafia and both godfather games. If I had to choose one it would be Mafia since I never had the chance to play it.