Your game looks cool and I wouldn't call 2k sold copied in a few days for an unhyped/unknown indie early access title bad. On the other hand you have an interesting price-tag for an early access game (€20) and very tough competition. I.e. I bought torchlight I/II for €20 each (as finished product).
Eventually the tough competition, Dialblo III, Torchlight, Exil + dozen of indie hack'n'slash roguelikes, all trying to bind players for a long time, will make your life very hard.
Nostalgia and art style alone is not enough, you need a feature which makes your game unique compared to your competition. Torchlight would be never such a success if they would have released the game after the Diablo III release. This + early access + price tag would be a reason to avoid your game for now.