What is the easiest game you have ever perfected in Steam?

The Blackwell Deception. The game is very short and the achievements are all part of the game. The only one I don't have is 'Listen closely, now' because it's broken.

Long Live The Queen wasn't too difficult :)

Stacking, Costume Quest.

Incredipede

Stacking
To the Moon

The 39 Steps

DLC Quest doesn't take much time or effort to get all the achievements.

Thomas Was Alone. The game's quite short and you can get all the achievements simply by playing through it. (Except for the "die 100 times" achievement - IIRC this was my final achievement, and I started the game and suicided a bunch of times to get it)

The first game I perfected was almost Shuggy. I had one challenge to beat to get my final achievement, but when I sat down to do that one I discovered that there was an update that arrived that day which added a new one for beating all of the co-op levels :p

Goat Simulator :p

The topic inspired me to go and do the Free To Play ones.

Had to rename one of the commentary tracks as it was bugged out, but yeah, that was very easy indeed.

deathspank 1,2,3
fallout nv
skyrim
puzzle world

although the bethesda games are buggy and hell and as yet i don't actually have the last achievement for both of them

Incredipede, achievement-wise.

Hexcells

fortix

I think the only one I have at 100% is Master Reboot. Is not hard and despite I used a guide to find some ducks, it's easy and fun to complete.

TWD Season 1, also I'm about to get Wolf Among Us one, when the last episode come out.

Indie Game: The Movie. That Team Meat commentary was great.

TWD (never got DLC though). Console games there are a few sports games where I got 100% in a few minutes but I dont remember which.

Goat sim is pretty easy too.

Eversion ranks pretty high up there.

stacking