Played through 3 series(6 chapters total) came with this collection, all played on Badass(3rd) difficulty.
This game is quite hard as you get no armor(Thus baddies doing good amounts o' damage if you're too close to 'em) and health items(Beers, Whiskeys, Pies and Snacks) have side-effects if you ain't careful with Alcohol(You get drunk, makes things harder and funnier) and Guts(Think when you fart while you're tryin' to sneak around) gauge on the HUD.
Weapons are pretty much basic but Chicken Crossbow(available in Rides Again) and one of the Alien Weapon(It's so hilarious that you gotta find it on yer own) are my all-time favorite weapon of FPS games I've played.
60'ish musics are good for me, so were Leo and baddie's voices.
Graphic's not as good as Monolith's Blood(it's same Build Engine game), but RnR's got its own style.
Pros : Massive amounts of Humor and Stupidity factor, overall hard combat(the way I like)
Cons : Confusing map designs, overall hard combat(people may hate it though)
Enough readin' here, go get it and blast 'em!