Pretty much every game aimed at young males featuring guns/violence tends to try too hard to be mature.  Too many to bother listing, clearly.

If you're playing online and there's a 12 year throwing out profanity and racial abuse, then it's probably a game that's trying too hard to be mature.

There are almost no mature games from my point of view, so no one is actually trying. For me mature has seldom to do anything with blood and gore.

The only mature game I can think of which also is trying a bit too hard is The Witcher.

READ DEAD REDEMPTION

Wii Fit !!

God Of War

I don't think the aim of gory/bloody games that glorify violence is to try to be "mature", they actually just try to appeal to their niche (young males).

Generally speaking, I find that almost any game which actually gets an M rating or its equivalent is "trying too hard". You can find more actually-mature games in the T rating (or its equivalent) nowadays, and sometimes in even lower ratings, than you can in the M rating.

ANIMAL CROSSING!!!

What with a burdgeoning mortgage, never ending payments and a corrupt loan shark, it's obviously trying way too hard.

Gears of War