There's a really nice base for an expanded and juicy game. As it is, it needs a bit of checking-up (especially with the walls' collision and maybe making the minimum speed for a hitbox slightly lower, for example), but there's already some really cool stuff that you managed here! The particles, speed effects, and overall setting of the room worked nicely, as well as the classic back-and-forth of offense and defense. I will say that it's relatively trivial to continue surviving, though. What if the player can curve around objects as well, grappling them and then turning around them? This would make movement more dynamic (if you added, say, nodes which could be turned around, or just making any surface like that), make it a bit harder to master, and it would throw a wrench into the movement in such a way that could fix the problem of a player just optimally escaping right as they've done damage. This way, they'd need to build up angular speed, too, and be more considerate of which enemies they'll accidentally be running into while trying to flank them!
TL;DR: I enjoyed the game! Good stuff. If you want to expand this, consider adding some curves to the player's toolkit by allowing them to swing around things, and add some tunes.
Cheers!