'I'll see you in 3+2i hours'

yep

I wondered that too.

Yep. I thought it would be apt for a difficult level showcasing grass and hedge.

When the arrow moves to the right, time is allowed to move forward. If a door is opened or grass turns into a hedge by stepping on it while time moves forward, this action is logged by the arrow. When the arrow moves to the left, time moves backwards. Inputs in backward time are resolved by finding a state from which the input would lead the player into the current state of the level. Essentially, if you were to make a bunch of inputs while time moved forward and then pressed the same inputs in the opposite order while time moved backward, you'd arrive more or less where you started from. For example, while time moves forward you can push keys, but while it moves backwards you can pull them (pulling is random because there's a chance the player was just walking towards the key in reverse instead of pushing it in reverse). The arrow turns around when facing most objects - I consider its ability to pull keys a bug that I wasn't able to fix. The way the baserules are set up does lead to potential paradoxes moving backward, like when a door is unopened onto a cliff (how would the key have opened that door) or when the player isn't standing on a hedge when the arrow reaches a sprout (the player is supposed to un-turn a grass into hedge at that step). Paradoxes create a question mark to indicate the cause and the level is destroyed shortly afterwards to resolve it.

@@hutthutthutt7321 that clears it up. Thanks! Excellent puzzles as always

While time is moving forwards, you can walk off a wall because that's how the game typically handles the interaction, so while time is moving backwards you can move onto a wall because it's the opposite motion of walking off. For the same reason, walls cannot be walked off while time is moving backward because they can't be walked onto while time is moving forward. One-tile thick walls can be traversed by moving into it while time moves backwards and back off while it moves forward. As an aside, it's impossible to cross a two-tile thick wall with this method because you can't go from a wall to a wall in backward or forward time, so the door must be opened to win.