I really like the tiles concept could be really improved. Into a futuristic like game with neon and stuff like that. But I have read the description so I wont give much ideas about graphics but I see some improvments to the player movement.
> Player moves quicker diagonally (it's easy to fix just multiply your x and z speed with
the absolute number of your normalized x and z speed kinda like this
Vector2 Movement (changes when you move) Vector2 OutPut (How player moves)
I put it as output because I dont know if you are using rigidbody movement or character controller
Vector2 OutPut = new Vector2(Movement.x * Mathf.Abs(Movement.normalized.x) * Time.deltatime * speed ,
0 or rb.velocity.y , Movement.y * Mathf.Abs(Movement.normalized.y) * Time.deltatime * speed)
> For the jumping (because you wrote you want to change the gravity a bit) it's just a matter of changing...
(if rigidbody) increase the gravity factor
(if character controller) set the gravity force higher or multiply y output when < 0
Hope I helped :D