Bit of a delay because I forgot about putting up my #40 because I was too deep into playing A Link Between Worlds ... Anyway, there's still time until I put up the #39, so here's the #40 and the hint:

#40

'Luigi's Mansion 2'

for the 3DS released in 2013.

The newest game on the list is 'Luigi's Mansion 2', called 'Luigi's Mansion: Dark Moon' in the US. It actually replaces the GameCube game 'Luigi's Mansion' on last year's list. 'Luigi's Mansion 2' is essentially the same game as the original, but better. Luigi once again sets out to hunt for ghosts. Unlike the first game, this time Luigi's journey takes him to multiple mansions, instead of just one, each with their own theme. There's a Haunted-House style mansion like the one in the first game, an overgrown tower, there's a clock factory, a frozen mine and finally a large mansion that includes all themes.

The different mansions add great variety to the game. Where the first game made the player go through a very large mansion that looked the same everywhere, 'Luigi's Mansion 2's' mansions each come with there own hazards and their own style of puzzles. Sadly though, this did take away a bit from the personality of the first game, also because the mansions don't have ghost forms of the original inhabitants like in the GameCube game. However, the added gameplay variety and extra functionalities of Luigi's vacuum and flashlight, greatly outweigh the cons.

The best part is actually the way it looks and uses the 3DS's 3D effect. The game has the best 3D effect I've seen yet. It's not really necessary to use it like in Super Mario 3D Land, but it gives an excellent feeling of depth. Because the game almost exclusively takes place in a series of small rooms, everytime it looks like you're actually looking into a pretty diorama instead of onto a screen!

#39 Hint

This famous old platform-adventure game, the very first in a long-standing franchise, was released on a great many different platforms from consoles to portables to home computers. However because it would sometimes take years before a port came out on something else, the newer version would look vastly improved from older ones. In those early years, up until '3D', the games would use numerals, but after that they would give each new game a subtitle instead. Also, a couple of years ago, a remaster was digitally released for modern platforms including the HD-twins and mobile platforms. Even a live-action movie was made (which was based on another entry in the franchise)!

41 - Final Fantasy IV

This is the 1st entry of the series in my list, but not the only one. 

This game was my 2nd FF game, where I played it first on GBA, then on DS and lastly on Eshop, if I remember correctly. The gameplay is exactly what I want from this type of genre. It was simple and not much more than that. Then we have the plot which was great and the characters as well. What is there not to love about this game? There is not much to say, but I've had fond memories of the game and have played it through 3 times, any game that has that is a game that deserves to be here.

Hint 40 -

This was the first game to be set on the world of one of the biggest games gen 7.

Hint for #38: Maybe this should be 9 places lower...

You know me well :)  But yes, my love for Bullfrog places this game much higher up my list.  Not know of any games out there with "monkey assistants"?  More specifically, a dedicated mode of monkey assistants?

Prince of Persia?

Prince of Persia is right!

Quite a long clue, but I couldn't come up with something good from the game itself... I thought "Starting from level 5 there's colorful walls" or something didn't do. I think I arguably have the best version, the Mac version. It's leagues above the DOS version and the console ports, the prince actually looks like a Persian prince.

Monkey assistants, monkey assistants... I got nothing. Don't know many games that have monkeys period actually, and I'm resisting Googling it. 'Hospitals', 'virusses' and those other weird things sounds like some kind of surreal shooter game...

Maybe something like Bioshock (though I also don't remember any monkeys there either)?

Or... surreal... Unreal? Didn't play that though .

Phantasy Star Online is correct.

I played this game on Dreamcast first, but then played Episodes 1 and 2 on Gamecube.  Then Episode 3 which was disappointing, but I still own it.  Then finally it's best on PC with far more hotkeys and Episode 4. 

The game is a Diablo clone, but heavily action oriented.  While the gameplay is very stiff and a little slow, it's for some reason a lot more enjoyable to me than the Universe/Portable series.  It's like the stiffness of the game is an quality that makes it a better game because each action you make needs to be that much more precise.  Timing is also required in Phantasy Star Online when using guns or weapons to do combination attacks for melee characters while every enemy has an elemental weakness and strength for  those playing as magic users. 

Now we're getting on the right lines.

Timesplitters?

There we go ;)

Timesplitters 2 to be precise!

Hint for 38.

Good sticky grenade inspired by Halo.