Where do you begin with a game like Risk of Rain? It's so new and original, yet so classic and oddly memorable that we can all adapt to it rather quickly while not feeling like we're repeating something playing it. Most "pixel games" as they call them I see now are simply normal games... with pixel-y art styles. This is one of those games that actually blends well with the art style, and I wouldn't have it any other way. Let's talk about gameplay for a sec.
Gameplay: Risk of Rain will kill on your first run. If this does not happen, you are probably a carrier of Jesus' will and strength on Earth, because it's pretty dang hard to pick up on your first go. But to help, I'll elaborate on just how NOT to die. You are given the Commando to start out with, and classes like the Bandit, Enforcer, and CHEF will be easy to get early on. Every character has 4 skills, kind of like LoL, except you don't have a basic attack outside of them - They're all you got. Most classes tend to have a movement-enhancing skill in their third slot, and a powerful skill in their fourth. The Commando is no exception. He has 4 basic skills which are very easy to learn and starts with above-average high health to help beginners.
Unlocking Stuff: Unlocking stuff isn't as easy as you would think. You're probably going to start on Drizzle, the easiest game mode. However, if you're a wimp, the game won't save any of your progress (This includes item logs), and no monster logs will drop either. If you want 100% completion, you're going to have to step it up. Most characters are unlocked by doing special things or filling requirements. No surprise there. The Huntress and Mercenary are pretty hard to get, asking for 15 monster logs and 5 game-wins, respectively. But don't worry - You'll get there if you like the game.
Items and YOU: Items are, without a doubt, THE most key tool you need to survive the night. When you start out, you will find items randomly from boss kills, chests, imp vases, shrines, and other places. Chests require money, imp vases require you to hunt down and kill a few frantic imps, shrines are like casinos, and bosses should be obvious - Kill em for good stuff. Most (Keyword - Most) items can stack. A few, like Thallium, can not. This is why the RoR Wiki is your field guide for items here. Items give you various buffs and bonuses, and have the power to make or break you depending on how you use them and your luck with finding items that suit you. Once you start picking up Artifacts, hidden items that you can activate to change gameplay once you die, quit, or win, can alter some things - But I'll let you figure that all out.
Difficulty: There's two ways this game changes difficulty - One, by choosing your difficulty on the character-select screen, and two, by slowly raising it during gameplay at a speed dependant on what difficulty you chose. This makes for very adjustable learning curves that will suit you everywhere. Artifacts can also help or hinder you if you're good at using them or not, for example; The Glass artifact cuts your health to 10%, but gives you a HUGE damage boost (Used to be x5 damage but they nerfed it, I have no idea what it is now - Don't worry, it's still fun as heck if you don't get hit!). Remember to start and progress at a rate that you're comfortable with, or else you might not have as much fun.
Conclusion: Oh yes, this is a game you need. Don't even ask why, just get it. It's 10 bucks. It's awesome. Once you know how to use and abuse the artifacts and characters, you'll pretty much be playing something like a God Simulator with every run, finding new ways to use your characters, match items, and have fun with MULTIPLAYER - That's right, MULTIPLAYER! Also, achievements in the form of READING AND KNOWLEDGE! Also, THE GAME LAUGHS AT YOU WHEN YOU DIE and gives SNARKY REMARKS! The art-style is AMAZING! The music is AMAZING! The gameplay is BONKERS RADICAMAZING TIMES TEN! Just! Get! This! Game!