Recs.
Updated
Path of Exile is a free to play action-RPG game similar in style to the Diablo franchise. A game focused on deep customization through using unique feeling characters. This is all offered for free, with in-game purchases available for cosmetic items and improved inventory storage.
SpecsUpdate
Pros
Pro "Racing" provides a great competitive aspect
Racing on Path of Exile are short burst (generally between 1 to 4 hours) play modes, in which you can earn points by doing specific things. Entering areas first, getting the highest level, furthest along, etc., will all grant you extra points.
These points are shown on the season's ladder, and can be used to redeem prizes.
Pro Completely free to download and play
Just install steam and download the game. No purchase required and the only thing locked behind paywalls is cosmetic accessories and inventory slots of which you can waste money on cosmetics, but you won't fall behind if you don't want to spend money.
Pro Expansive skill tree
While it may be difficult to take in at first the skill tree in Path of Exile is quite expansive allowing for many areas of the characters skills to be customized. The tree is so large there are numerous guides online on how to build specific optimized characters as well as an unofficial companion app for Android.
Cons
Con Very high learning curve
There's quite a lot to learn when starting to play Path of Exile. There are the mechanics, the crafting system, and the skill gem system. However, the most intimidating factor is the massive skill tree with over 1000 skill nodes, 6 classes and 19 subclasses, allowing you to create hundreds of unique builds. Unfortunately, creating a functional build is really difficult, taking hours of theorycrafting, so it might be better to stick to guides as you're starting out, unless you're fine with possibly messing up.
Con Endgame can get really repetitive
It takes an exceptionally long time to get any wealth, useful items, or access to endgame bosses in this game. You endlessly farm the same maps, hoping you'll get lucky with a few good items, but that usually won't be the case, which can be really discouraging to keep playing. This is made worse by the fact that your character progression comes to a grinding halt near the upper 80s of character levels, requiring you to buy insanely expensive items to feel any progression at all. If you don't like grinding, you'll get quickly bored of Path of Exile.
Con Clunky trading system
The western PC version of Path of Exile currently requires using an external site to find deals or sifting through scam attempts in the trade chat. After you find an item you want to buy, you need to message the seller, and if they respond, enter the same area as them to make a direct trade. There is no auction house, no mail, no automated trading posts, and to sell stuff you have to buy a premium stash tab via a microtransaction.
Con Anti-experimentation for new players
The game heavily punishes any experimentation for new players. Unless you have near perfect understanding of late game and the various viable build-options you are more or less unable to experiment your way into viable builds (and the options for correcting mistakes are limited at best). So, unless you are fine with having to scrap a bunch of characters for being sub-optimal, you are more or less forced into following player-made guides to learn the game rather than through engaging with the game itself. This may or may not be a problem for you.
Con Huge time investment needed
As any ARPG worth mentioning, you'll eventually have to invest time into character builds.