I need Game Suggestions ($30 or less)

Just Cause 2 babyyyyyyy

Mafia 3? :P It costs 31,67 euros in a key site, as I'm seeing right now. Otherwise, Saints Row 2 is an awesome game (just don't check its sequels - EVER!). You can also check out The Godfather II, but it's not that good.

GTA 5 on a sale maybe, Counter-Strike: GO, the Half-Life series, Civilization V, The Walking Dead, Rocket League, Ark: Surivval. I don't know there'es a lot of good titles around!

I've played recently "Remember Me".
Its sort of restricted open world. I've really enjoyed it and you can get it pretty cheap

EDIT: Just checked and it has been for 5.5€ in the past

Highly recommend Dragon's Dogma

Mad Max follows the WB game "formula".
The combat is the exact same as in the Batman Arkham games and Middle-earth: Shadow of Mordor.
If you liked the combat, go for those.

For games like Mafia, try GTAs, The Godfather 1/2 (they aren't on steam thought), Saints Row 2 (3/4 went wacky, they can be fun, but it's a completely different atmosphere) and the amazing Sleeping Dogs, which is my favourite of the bunch.

How about Borderlands 2, RAGE or Saints Row IV - you can probably pick up all 3 of them for that price if you are using keystores.
If you are interested in Fantasy games as well, you could try Skyrim.

Mass Effect 1&2, since people mentioned a bunch of fantasy/"modern-day" games.

Sleeping Dogs~

If you want a game in the general vein of Mad Max, then:
-Just cause series (though the first one can, and should, be skipped)
-Assassin's Creed series
-Shadow of Mordor
-Batman Arkham series (more so the post Asylum ones)

For games more like Mafia 2
-Mafia 1 (get a boxed copy!)
-GTA series
-Sleeping Dogs
-(Watch_Dogs to some degree)

Shadow of Mordor is great you can get it for $5

Dying Light The Following Enhanced Edition goes on sale for $30

Definitely play the Batman Arkham games if you like Mad Max. If you liked the driving in Mad Max, then you'll really like Arkham Knight. The Batmobile was one of my favorite parts of the game for me.

Company of Heroes 2

Shadow of Mordor would be a solid pick after Mad Max

The saboteur

dishonored

farcry 3

S.T.A.L.K.E.R.: Call of Pripyat

Metro

Skyrim, Fallout series, Red dead redemption, Farcry 4 and Witcher 3 wildhunt. witcher 3 is 30$ right now on steam too. .

How about Max Payne 3

Do yourself a favor and save for Civilization 6, then preorder it from cdkeys and be happy when it comes out. That's what I did and am waiting for that game, and it actually looks really promising - including all expansions and things from Civ 5 with cartoonish graphics. Just... Amazing! 8)