I must admit, I have tried many times over the past couple of years to get into Hydra Slayer and failed. I'm not sure why, since I think the base gameplay is very cool. I guess part of it is my many attempts to try the Android version, which has some basic interface problems.
But the look of the game is also a bit of a thing for me. Too many garish colours, especially those horrible magentas and cyans. With the NotEye integration can you not now choose a better palette?
The starting screen is too messy too, in my opinion. I'd appreciate something cleaner, with a separate help screen for all the extra info, a bit like ADOM's start menu. The various options presented with their keyboard commands highlighted look untidy and should be split into a game options screen.
The racial descriptions are longer than they need to be, or at least could have a little summary of the key traits at the start. For instance:
Human
* No special strengths
* No special weaknesses
* More versatile overall
Titan
* Hits with both weapons at once
* Half regular speed
* Cannot carry items between levels
Centaur
* More skilled with bows
* Cannot do sweeping attacks
As much as I normally prefer ASCII, the animated tiles are now more functional in many ways. Seeing flames on a fire hydra and linking that to your flaming sword is much clearer than trying to match colours. The tiles themselves... meh, though I like the hydras. I think the main character tiles could use a bit of touching up (maybe with a more cartoony style?), and scrolls should be a lighter colour to stand out. I'm not big on the dark floor tiles either.
A tutorial would likely help new players. Not sure if you have the time, but a simple set dungeon with a couple of hydra types and weapons to pick up and scrolls to use would really boost the game's accessibility.
Death is a little poorly managed at the moment. The game should properly pause and change to another mode, with perhaps a simple menu offering "1. Character dump, 2. Restart human, 3. Restart titan, 4. Restart twins, 5. Restart centaur, 6. Exit game".
For the Android version a touchscreen HUD would be hugely appreciated. Having to go into the menu to pick up items and perform other common actions is very cumbersome.
As for general gameplay, it's balanced, fun, engaging, challenging and unique. I'm not very good at it, I think partly because it does require such concentration and too often I play when tired. I'd maybe appreciate smaller levels and smaller FOV.