You can tell this is by the Guacamelee team from the art style - and it has just as much character and attention to detail as those games. NSTW is an action RPG, but has a huge focus on unlocking abilities and characters throughout the game. You play as someone who finds a wand with the power to transform you into one of 17 different forms. Each form comes with a passive ability, and 2-3 unlockable active abilities that you can then use on ANY of the other forms. It allows you to create very diverse character builds. These forms level up by completing form-specific quests, which also teach you how to use the abilities well together and give you ideas.
Aside from the form-shifting gameplay, it's basically a dungeon crawler with lots of quests and an overworld. The world is littered with dungeons that you need to beat to find stars to unlock the few Legendary dungeons, which lock progress in your form quests and make you assemble a build that works well. The world map is colourful and has several different biomes. Quests from the NPCs you meet are varied and interesting, and aren't simply just "go kill these". For example, one of them was a slug who's wife had died - and he'd heard of a slug necromancer who may be able to bring her back. Thanks to the form shifting abilities, you can combine the slug form with the necromancer's Summon Demon ability to bring her back to life.