This is one of the games that would make me go crazy and frustrated, but I'll still play it cause it's fun and challenging! I think adding much more types of grenades will be a lot of fun, so that once the player gets used to the mechanics, he or she will always need to adapt to new types of grenades.
Also, the art style used for a game is amazing, seriously. And you have one of the best thumbnails for a game, it attracts the attention well. The game is under-appreciated, though, but let it not distract you from continuing working on it, because it's extremely good and has a potential! Best of luck