Fortunely, this game is alot deeper than that.
Imma try to explain it as good as I can, even tho I've only played like 5 hours total in this game.
So normally you play 5v5. Goal of the game is killing their base. Before game starts you choose what champion you wanna use. Map is built into 3 lanes. (Imagine holding the line scenario) where allied minions and spawn from your base, and enemie minions from enemie base. Each line has 3 towers. The more towers you kill the more mapcontroll you get. Also if you kill all the towers and also a bigger building then superminions will start spawning at your lane. Makeing it even easier.
Each Champion has its own starts, passive ability and 4 active abilities. This abilities is very different but most of them helps you in fight. Also combo's of them is really good. On my Morgana-champ, I've had most success with a QWR combo. (active abilities have hotkeys QWER)
Ingame you get cash from everything you kill. (alot from killing enemie players and towers) This money is used in the shop at ur base. There is alot of items you can buy, so you need to choose a build that works for your champion, also works against ur enemy.
You also get experience in game and lvl up. This boosts your champion. Max lvl in game is 18.
Outside of the game, in the lobby if you will, you also gain experience points and something called IP. In the lobby you can max get lvl 30 (this is when you can start with ranked game). Lvling up here gives you more masteries points, and more slots open in your rune-book. Masteriepoints you can choose between different boosts in offence/defence/utility.
Runes you buy in the store for IP and also gives alot of different boosts. You also get 10 different pages in each, so u can use more than 1 champion.
So to go in depth of this game you have 3 strategic builds to go. Also this game is very teamplay oriented. So teamplay is very important.
Summary: Actionfilled strategygame that I find really fun and addictive. It's the best free game I've ever tried. Hope this info was helpfull (and accurate

).