Well, it is a roguelike, in that every time you start you get a new randomly generated world. It is pretty difficult, at least it was for me starting out and getting used to aiming arrows. You move around the world and kite enemies, and lead them into favorable fighting areas. As you go through the level you earn gold that you can use to upgrade your arrows and or get some health back and maybe other stuff. At the end of the level you enter a dungeon and then there is a boss fight, and then the world resets.
As for how much content there is, I haven’t played it a whole lot so it’s hard to say. As you accomplish things in the game, you unlock new things for further playthroughs. For instance, if you kill something like 10 archer enemy types in one run, a new type of archer might open up. I don’t know how many enemy types you eventually unlock, although it gets significantly more difficult. For instance, when you start, there are only 3 main enemy types, an archer type, a sword man guy, and a zombie guy. Even though that doesn’t sound like a lot, you can be under a lot of pressure especially when you enter a big room full of enemies with zombies rushing at you, the swordmen approaching you and at the same time having to deal with the archers. Generally I will exit the room and start killing enemies as they come after me through a doorway, but the archer’s can also teleport! so it can be a bit dangerous.
RIght now I am dealing with significantly more dangerous archer types that fire multiple rounds of arrows (so that if I’m facing even 2 of them at once I’d better move to a more favorable position), swordmen with shields so you have to aim at their face or non shielded body, and I just unlocked some kind of super dangerous archer enemy type that fires a very quick arrow directly at you that is much harder to deal with and block.
I’d say the replayability is definitely there, because you always have a different level loadout, you’re unlocking new stuff, and you can go for high scores on the leaderboard. The game is pretty difficult. Some of my runs only last around 10 minutes or less and the game is getting significantly more difficult, although now that I am becoming familiar with the game I am also a much better archer =)
Unfortunately I don’t know how many new types of enemies open up so I’m not sure how long the content slowly feeds in, though I have seen some youtube videos with enemies I’ve never encountered before. You could wait for more content, but I think what is there already will last you for a long time, especially if you’re going for high scores which I’m nowhere even close to approaching =)