Alchemist’s Castle is a short Metroidvania game lasting around 2 hours. At the very beginning, you drop down from a large height and hurt your leg, but it is not clear that it means your jump is disabled. I think the text was something about barely being able to walk - but your movement is not impeded.
Not being able to jump forces you down a certain path until you recover; which opens up many more rooms. You get simple abilities like attack, run, double jump. You also have "coyote time" style jump, so you can fall off a ledge then jump. Combine that with a double-jump, and you can make some interesting leaps later on.
There’s some optional scrolls to collect which deliver the story.
There are save-points scattered around but some can be quite sparse. I found that sometimes you had a choice of exits in a room, and one would contain a save-point so you could miss it. There's no dedicated save-point rooms like in some Metroid games, so they aren't so easy to spot or predict either.
The lack of save points can be frustrating when there are green water pools which is instant death.
Your attack is an explosive ranged attack which is hard to aim. Given the trajectory, you can't always hit things right in front of you. Instead you have to back off then attack. At the start you will just have bats and rats, although the bats take a few hits to take down for some reason. Later on you find ghosts which can travel through platforms and always move towards you. These are even harder to hit.
The invincibility frames of hit enemies seem a bit too long, and you can easily take damage if you try to rush before the sprite has fully cleared. You seem to be able to damage yourself from your own explosive attacks too.
Towards the end of the game you get an explosive upgrade, then several screens later, there is another one which seems like bad design. There's a drastic increase in enemies around that point, so at least you have an increase in power to deal with them.
There's a few points where it is not always obvious where to go, especially when it might not be clear you need a new ability to progress. Some rooms definitely looked optional, or you needed to come back to them - but they weren't; it really was the path forward. I suppose there’s always moments like this in the genre, even in highly regarded games.
There’s a few areas where you need to drop crates, but you don’t get a chance to view the level layout so you are guaranteed to mess up and will have to backtrack out to reset the room. There’s one puzzle where you have to drop a crate on top of another crate, but you have to make sure it is offset to create a stair structure. It seemed a bit jarring to me to do this. I think in other games where you need to do that, you would be able to reposition the crate whilst it is on top of the other; but here you do not (unless there’s another crate you can position horizontally, then you can climb on top to push the other crate).
There's a bug that when you launch the game again, you can't attack. But if you go into the options and select the option to reset the key bindings, it will work once more.
It definitely has some moments of frustration, and I have plenty of criticism, but it is a decent and brief Metroidvania. I did generally have fun with it.