The time travel mechanic is really cool because it's like you're exploring three maps at once! I like the art style too (especially the art at the start).
Sometimes I did have multiple enemies spawn on top of me if I was standing at their spawn point when I time traveled - maybe a second of invulnerability when you time travel might help to prevent players from instantly getting hit by an enemy. Or maybe enemies don't attack until one second after they spawn, just so players have some time to react.