(Note that these things might not be added)

Water gun: If you have played the 2nd demo and read the virtual manual you would know.

The Great Wava Fountains and a lava gun power up: If you have a water gun and find a Wava Fountain, you can go up to it and press X on your key board. Once you do that, your water gun turns into a lava gun and if you do the same thing again but with a lava gun, it turns into a water gun. The reason these might be a thing is another feature that might be added: fire and water enemies. Pretty much fire enemies are weak to the water gun and water enemies are weak to the lava gun.

Skin: I like character customisation in games so there would be skins that you buy with the games virtual currency that I don't know what to call yet. No microtransactions with the currency either.