Version differences
Out of all platforms, the Steam version is the fastest but requires a good enough computer to run smoothly. Due to individual differences in runners' hardware, exiting the game completely is banned to eliminate discrepancies in game launch speed (which means the Gramby cutscene skip on Day 1 saves slightly less time, and resetting each attempt at the fishing contest takes longer). The game itself, however, should run exactly the same on all computers that meet the minimum requirements.
Switch and PS4 are slightly slower than Steam, but still faster than the original PS1 version, though the game hasn't been tested on the backwards-compatible PS2.
Languages
Japanese is faster than English due to less text. For non-Japanese speakers, basic knowledge of hiragana and katakana is highly recommended, mostly because of the Adder minigame. Being familiar with Chinese/Japanese numerals also helps with the firework minigame, but otherwise knowing kanji is not required.
To change the game language on Switch, go to your system settings and change the console language to Japanese. To change it on PC and Mac, press L and select "Yes".
Character naming
Like with many other RPGs, it's best to name your character a single letter, since it will occupy the least space within text boxes whenever it comes up during dialogue.
Compare: "Do you happen to be JOHNDOE? JOHNDOE, is that you?" "Do you happen to be A? A, is that you?"
When the naming screen comes up, you can quickly press [Action] [Start] [Action] to name your character "a" (or "あ" if you're playing in Japanese).
Diagonal speed
As demonstrated in the video above, walking diagonally gives you the same vertical/horizontal speed as walking straight. This means that, for example, if your destination is directly to the south of you, walking diagonally down is just as fast as walking straight down.
In-game clock manipulation
When there is a text box on the screen (e.g. dialogue, a sign post, or an animal file) the in-game clock is paused, but any NPCs and animals that are on the same map as you will continue their behavior. This does not work with menus, it has to be a text box that you open by interacting with something on the map.
Day-night transition
When day turns to night, a short animation will play that will waste a couple of seconds. However, there are certain maps where this animation doesn't play, including the castle's hallways, Burrn Hall, and the Mushroom Forest. It's recommended to be on these maps during the day-night transition whenever possible.
Skips
moon is a pretty tightly programmed game with no complex movement or collision. As such, there aren't many exploits to be used in speedruns.
Gramby cutscene skip
You can skip the cutscene that plays at the start of day 1 (the one where Gramby gives you clothes) by resetting the game and reloading the save. The game saves your progress right after the first night cutscene with the Queen, so make sure not to reset too early. This saves about 13 seconds on the Switch (and potentially more on PS1).
On the Steam version this is performed by changing the language in-game twice. Exiting and relaunching the game is not allowed because of inconsistent speed (see above).
Fountain skip
You can skip having to toss a coin in the fountain to catch the Yenom Frog. By standing in a precise spot at the upper corner and aiming down-left, you can reach the Yenom Frog while it's on the grass. This saves about 4 seconds.
Re-men glitch
By completing the Re-men survey on another save file, returning to the title screen without closing the game, and then starting your run from a new file, you can complete the survey again by just talking to the first Re-man twice, resulting in a quick and guaranteed 4 Love.
You can return to the title screen on all versions by waiting for the Action Limit to run out, triggering a Game Over. The Steam version also lets you change the language by pressing L on the keyboard, which achieves the same result.
