Pick a new game for me! (No giveaways. Sorry!)

Try the Hector trilogy, since you have found other Tell Tale games decent.

Does this apply to game you have, or both?

Stanley Parable.

Here is one for you

modern warefare 2

i was gonna say half life 2 because its a great game bu you've mentioned it

Psychonauts might be for you. :) It can get hard and tense for the boss fights, but overall it's a super fun, awesome, hilarious game (by the same makers of Brütal Legend, too). :)
Another Double Fine one, haha, is Stacking. The story might not be as strong because of the way it's told, but it's fun and relaxing, very casual. And there's a decent hints system that's very accessible but not compulsory which also helps with the casual nature of the game. :) There's also a lot of humor in the particular personalities and actions you get to take command of. :)

If you like tower defense at all, I've been really liking Defender's Quest -- it's a hybrid Tower Defense/RPG with a storyline, where the "towers" are actually PCs who you get to level up and develop with gear and skill trees. It has a fun storyline and engaging characters, and the game mechanics fit the story, and the difficulty levels are incredibly scalable. I found playing the basic campaign very easy and have been running through more challenging modes since then. If the basic campaign is a bit much, you can turn up the XP/cash rewards a bit in the Accessibility menu and tone it down even further from the defaults. There's almost no branching in the storyline but I find it fun to go back and beat harder maps once I've leveled/geared up my party more, play it in hero mode, etc., so there is good replayability.

If you can get your hands on Grim Fandango (it's out of print so you'd need to find an old copy kicking around) it's really great, by the makers of Brutal Legend. A point-and-click adventure but very funny and with a lot of good detail, really a cut above the rest of the genre. I haven't played their Monkey Island series yet but it's also supposed to be very good. The Longest Journey is more tense but also has a lot of detail and fun characters and humor.

scribblenauts and brothers: a tale of a two sons

Deponia, Chaos on Deponia, Goodbye Deponia

Assassin's Creed (I recommend AC2; It's easily my (and many other AC fans') favorite)
The storyline is awesome, and the game is fairly easy (although at first you may not be familiar with the controls etc. but a few hours in you will be playing like a pro)

Also check out: Defender's Quest: Valley of the Forgotten (Tower defence with a unique story)
It's a hidden gem that most people don't really know of. I personally didn't play it much immediately after I bought it (through a sale), but recently I have been playing through the game and it's quite enjoyable. Defender's Quest II is also coming out soon. It's fairly easy in that the difficulty is yours to choose. If you want challenge you can always revisit by playing the + mode.

Although it doesn't quite fit your criteria, I highly recommend that you play FTL: Faster Than Light!

It's such an excellent game, it's my second most played game on Steam with 94 hours recorded (with another 50+ hours played offline and on my desktop that's currently offline only).

There are also a ton of great mods tat add a little or completely change the game when you've beaten it to the extent that you feel necessary before using mods.

I can't praise this game highly enough!

It's more than worth the $9.99 price tag on Steam and it's currently 50% off right now for the next 36 hours!

I think you should try Gunpoint which is not too relaxing or easy but its still a good fun game that can be funny and has a good story.

Try "The Swapper"!!!!!!
it is touching, has a scifi-story an plays like a child of limbo & portal :D

"-Relaxed. I'm playing a game to have a little rest. I'm fine with some excitement, but I don't want to be stressed on most of the game."
"-Easy. I love games, but I'm not exactly "hard"core. I like to breeze through my games."
Sir, you need to play Dark Souls (and my real proposition is Kerbal Space Program, rly funny game sadly not too much if we talk about story)

dont starve is the best from your list i can play it like 3 hours without noticing that the time has past.it is an awesome game really worth a try and especially worth the money

Braid.

Try Gone Home. It's not much long but I think you will like it.

Mass Effect Trilogy, Dragon Age Origins, Brothers: A Tale Of Two Sons, Neighbors From Hell Compilation.

Try Thomas was Alone game, it was on Humble Bundle a while ago, and a great, narrative, relaxing puzzle game. you play as 'Thomas' a rectangle that has some interesting thoughts, that are all narrated. I'll let the game tell you the rest of the story, it truly is an amazing game!

Get Mafia II. It was the best game I have EVER played. You might already have it because it was free.