I really can't sing the praises of Torchlight 2 enough. A lot of people I know describe it as "Diablo 2.5" and to be fair, it kinda is. I maintain, however, that it's not a bad thing. Graphically, it's as pretty as anything I've seen Diablo 3 produce. Its interface will be instantly familiar to you if you've played Diablo 2, unlike D3 which looks like I'd have to learn all over again. It has a quest system overworld-and-dungeons combo you'll be familiar with from D2, a potion and scroll system reminiscent of D2's, an item transmutation system that's a very simplified variation of D2's, even tiny atmospheric critters you can squish underfoot, just like in D2.
That's pretty much where the similarities end. For one, your inventory is far more convenient. Gone are the days where you have to juggle space for every item - now everything takes up a single inventory block, and furthermore, consumable items and spells (more on those later) have their own inventory tabs. Gone are the skill trees, where you have to take this
skill in order to take that
skill. Now if you meet the level requirements, you can level the skill. You can even freely mix skills between various trees without feeling like you're penalizing yourself. Gone is the irritating stamina system - you can move at full speed, full time, instead of being forced to walk unless you guzzle potions. Gone are the complicated extra rarities of stuff - there's normal, there's enchanted, there's rare (which includes some sets), unique (also with some sets), and at the highest end, legendary. Everything drops, eventually. No need to jump through complicated hoops of requirements to get a particular item - if you're at the right level range for it to drop or appear in the Gambler Shop's inventory, you can get it, if you have the patience and gold.
New to the genre are permanent pets. They're more than just there to look cute. For one, they have their own inventories, which are as robust as yours. Load 'em up with everything you don't want to carry, like all those trash items you'd never bother with otherwise. Then, send them off to town to sell your loot. No need to stop adventuring or use a town portal scroll just to clean out the garbage! Your pet can even go purchase supplies for you while you're in the field. Just a brief one or two minute wait is all it takes to get whatever basic amenities you need to keep adventuring. More than just pack mules, all pets can fight, possessing a basic attack. However, you can also teach them skills, too. Ever wanted an alpaca that could spit fire and ice? How about a bulldog that shoots swarms of bees when it barks? Or maybe a necropanther - a panther necromancer, summoning skeletal archers and exploding zombies? Find the right spell scrolls, and your pet can do just that!
Speaking of spells, these little gems are throwbacks to the days of Diablo 1, where all the magic you own was found in the dungeon and learned the hard way. Spells exist in addition to your class's skills, and you can have a maximum of four spells. They're not unique to any class - any class can learn any spell, with the only restriction is having the required level or better. They range from passive effects to buffs to direct damage spells. Your barbarian, in addition to his horrific melee combat ability, can supplement his murderous rampage with fireballs, or buff up his attack and movement speed to get him into the fray faster. It all depends on what spells you find and learn.
Finally, Torchlight II does away with the slowness and stodginess of Diablo 2's gameplay. Characters are fast and dynamic, enemies are slightly fewer but more brutal, with many, many more enemies having special attacks and abilities, not just champions. You need to think on your feet a lot more, and use your skills intelligently and in good combination to dominate your foes. There's less a focus on the stats you fight with and more on how
you fight, and there's always numerous ways you can approach a situation with every class. As an engineer, do you charge in with melee attacks and rely on your armor and defensive buffs to survive? Or do you hang back with a cannon and blast crowds of enemies while your various killer robots do the grunt work? It's up to you, and both approaches are completely viable. In addition, enemies and the world feel more 'alive' - they don't just approach you in random themed hordes, but instead appear dynamically from the environment. Ezrohir ambushers will burst from the sands of the desert underfoot. Sturmbeorn raiders will leap from the cliffs overhead to challenge you. You'll encounter zombies and ghouls devouring a corpse, and when you kill them, the flesh-stripped corpse rises as a skeleton to fight you as well. Vile mystics will be found performing rituals upon desecrated tombs or will be trying to sacrifice innocent captives, and you can draw the attention of a lich by disturbing its grave. You can rescue slaves from packs of slaver-bandits, and be surprised when you fight a horrid monster, only for its even-more-horrid mate to show up and join the fight!
All in all, I consider Torchlight 2 to be a worthy entry to the action-RPG dungeon-crawler subgenre. It strips the BS out of Diablo 2, keeps what Diablo 2 did well, and then improves upon the whole formula without being as wildly experimental as Diablo 3 is. And hey, if you don't
like what Torchlight II does, vanilla? Well, it's mod-friendly, and has Steam Workshop support. If you don't like it, change it!