Taking a look through your library, I can see a couple that are "easy" to 100%, mainly that they do not require any serious sidetracking or grinding:

*Thomas Was Alone
Took me about 3 or so hours to complete 100%, in a single run - no real optionals except maybe "Part of the Problem", which you'll probably get by accident anyway. The "X" amount of Jumps achievements will probably unlock while you attempt to solve the game's puzzles, as will the 100 Deaths one.

*Superbrothers: Sword & Sworcery
Again, only about 4 hours to 100% completion but the problem here is that for two of the achievements you'll need to replay the final chapter - the first time by waiting a set amount of real-world days for the Moon to hit specific phases (you just need to start up the game on the specific date) for the "#honest" achievement and the second time to change your PC's date manually to reach the same Moon phase for the "Cheating Cheater" achievement. Check this forum post for more details.

*Deus Ex: Human Revolution - The Missing Link
Another relatively "easy" one, depending on how good you are with stealth. You'll probably need about 2 playthroughs total - one for "Factory Zero" (finish the game with no upgrades) and one for all the rest. "Out of the Frying Pan" and "Never Stop Looking" are story-based and thus, unmissable, "That Old Adage" (needs CASIE upgrade), "Apex Predator" (needs good stealth skills), "All of the Above" (needs Move Heavy Objects and Jump Enhancement upgrades) and "Good Samaritan" are either optional main mission options or side-quests, "The Learn'd Scholar", "Back Stage Pass" and "Never Forget" are exploration-based achievements.

*Costume Quest
For the most part, requires light exploration to find all the secrets (but allows backtracking, in case you miss anything). The only "problematic" achievement is "Tisn't The Season", for which you'll have to fire up the game during the 25th of December (Christmas Day).

Note that the final five achievements are part of the "Grubbins on Ice" DLC, included in the game but played seperately from the main campaign.

*Portal 2
You might want to ask around for a co-op partner for the ones you're missing, with the exception of "Still Alive" and "Talent Show" which are a bit tricky unless you've gotten used to the co-op campaign level layouts and solutions, the rest are easy enough to do in a single playthrough (about 1-4 hours, depends on whether either of the players has done the co-op campaign before).

*Deus Ex: Human Revolution
If you can stomach running the game again for a no-kill, no-detect run on Give me Deus Ex difficulty (easier than it sounds, you are allowed quicksaves), you can also do "Cloak & Daggers" (check a walkthrough for specifics), "Doctorate" (this list here[deusex.wikia.com] is very useful) and "Gun Nut" (fully upgrade the tranquilizer rifle, which you'll need for a no-kill run) on the way.

-- If you're feeling lucky, give Poker Night At The Inventory a try - it's very much luck-based so I can't really give an estimate on time, I've done about 75% of the achievements in 3-ish hours though.
-- Alternatively, try Shank if you prefer platform games, you can get the entire achievement list except "Backstory" (needs co-op) if you do a playthrough on Hard difficulty.
-- You're also missing the "Speed Run" achievement in Braid, you can either replay the game or check around on YouTube for a few speedruns to get the feel of the levels before trying it (if memory serves, you must beat the game in under 45 minutes).
-- Finally, if you are good at puzzle games, Splice might be a good option, as half the achievements are for completing puzzles and the other half for completing the Epilogue puzzles (unlocked when doing main puzzle strands with "Angelic" solutions (i.e. in less than the maximum moves allowed)).

Regards,
GreyGore

Thanks man, for taking a lot of time in writing it. I defenetly try some games from your list.

I go to astats, look at the people who have the most completed games and sort the list by "Hours Played" :-)

Wow, I'd really have to disagree with DXHR being easy, especially because with that no-kill achievement, sometimes an enemy gets killed inadvertently and if you don't notice, you'll have wasted a lot of time by the end of the game.

In addition, HL2, and HL2 ep 1 and 2 are easy to 100%, if you have them.

Stacking isn't too hard either, got 100% including the dlc in 7 hours.

wasteland angel, play story mode about 3 hours to 100%

Adventure games are usually easy to 100% becasue there is no room for grindy achievements or if there are some secret achievements it's easy to find a walkthrough.

Regarding DX:HR - I was mostly banking on ShockwaveNN having played the game once before, the fact that you can have an infinite number of saves, as well as the fact that any "accidental" deaths are mostly the result of Jensen knocking out/dumping unconscious enemies in the wrong places (such as rooftops and/or near water).

The best solution I've found is to avoid guards altogether; with the proper upgrades you can be stealthing in and out of cover from as soon as the abandoned factory level (remember, non-lethal and stealthy runs award slightly more exp. than run n' gun ones, so you can afford the cloak and energy conservation augments earlier). Barring that, I always made sure that any unconscious enemies were left out of harm's way (usually by carrying them into a "safe" room - such as toilets, storage rooms, cupboards and in one case, on a desk) before moving to the next set-piece/cluster of rooms/area.

Also, I never mentioned easy (although I do on the Missing Link one, with the "depending on how good you are at stealth" qualifier), I just recommended it on the grounds of not having achievements you need "200 hours grinding" to get. :P

Regarding HL2, and Episodes thereof: I find them very good choices as well, but with the caveat that you'll either spend a lot of time searching, or will be using a guide for both the Lamba caches and the Episode 2 grubs. In my case at least, I had to restart the game(s) one or two times when I'd found that I skipped a cache and/or some grubs and had to replay certain levels (the grubs are slightly easier, since there's only two levels to replay; on the other hand, if you miss a cache and don't know which level it was on, you might need to replay the entire game).

The three games in the Adam's Venture Series are all quite easy and short. A guide helps to speed them up.

39 Steps is very easy and hardly a game, more of an interactive book, but only takes a few hours to click your way through.

Botanicula only takes a few hours to do, has a lot of achievements and is overall very enjoyable. Would recommend a guide on the side though so you dont miss something along the way.

Unmechanical is anoother easy game to complete. Nothing too tricky.

Eversion - it took me 2 hours and is really easy achieve,

The Walking Dead - you get all the achievements just by finishing the game

DXHR - time consuming, requires patience
DXHFML - requires patience
Portal 2 - good luck with Professor Portal unless there is some trick.
HL2EP2 - the last achievo for defending the village is by no means easy, it's really hectic.

Fluttabyes. I just did it so fast.

Poker Night 2 is vastly easier than Poker Night 1. The first game has an achievement that requires you win a hand with a straight flush... if you're lucky enough for the game engine to recognize that you did it.

I just did Mark of the Ninja. Fun and not too difficult.

There are plenty of walkthrough videos of Defense Grid and Deus Ex to help with those. Bastion, too.

Ironclad Tactics, only 1 achievement and you can get it pretty much when you start up the game.