Moss Moss is a non-combat platformer by Noel Cody where you play as a little moss ball trying to fill the world with moss. Sometimes described as a metroidvania or "microvania" (but with only one post-game ability upgrade), the game features an 8x4 interconnected map, and your goal is to cover all the unmossed surfaces. Mossing up each screen spawns a leaf orb, grabbing which adds to the 32-step leaf path that lets you reach the top screen and finish the game. In addition, there are 15 spirits scattered throughout the game world, collecting which unlocks the full completion ending aka "Fully Mossed".

As usual for PICO-8 games, Moss Moss is free and can be downloaded or played online on Lexaloffle and itch.io

Settings

Emulator: libTAS v1.4.8
Linux MT 6.18.35.2-microsoft-standard-WSL2+
Ubuntu 24.04.4 LTS

PICO-8 version: 0.2.7
foreground_sleep_ms: 2

Cart: mossmoss-17.p8.png
MD5 (cart): 3f5de38c7e7381d0d163423e44292897
MD5 (game binary): dab42b06b1908bfac7210ed6c5f1c9a1

Our actions are standard fare for indie platformers: jump and dash. Dashing can only be done horizontally or diagonally downwards. The cooldown between dashes is different depending on if we dash from a grounded state (shorter cooldown) or dash mid-air (more than twice as long). However, we can always dash immediately whenever we 1) land on the ground from above or 2) get unstuck from a ceiling.

Every dash starts with a 2 frame freeze, so spamming as many dashes as possible is not always the fastest option. For narrow tunnels, especially if both top and bottom are mossable surfaces, the fastest method is repeating jump -> diagonal down dash, at a slightly higher frequency than the normal cooldown would allow. But for flat open stretches of ground, simply dashing horizontally obeying the cooldown seems to be more optimal.

When we push against a ceiling, we cling to it for a short amount of time, allowing us to slide along it and moss several tiles at once. Dashing along a ceiling also extends this clinging state until the end of the dash.

Our character freezes for a short amount of time when grabbing a leaf orb or a spirit, opening a breakable wall, bouncing on a cloud, or triggering a vine ladder. This frozen state doesn't affect bubble cycles or any other animations present on the screen. We can cancel out of the freeze by pressing jump.

I will be using a X-Y coordinate system to refer to specific screens, e.g. 1-4 is the bottom left screen, 8-1 is top right. The starting screen is 4-3.

This is one of the two parts of the run that heavily feature bubble cycles, which spawn at a rate of roughly 1 every second, leading to extensive downtime. However, we use tricks to skip a couple of cycles.

First, in the top right of 7-4, we jump immediately after sliding down a wall, which gives us an additional 1 pixel of height compared to a regular jump, allowing us to just barely reach the platform above without using a bubble. Second, in 7-3, we take each of the jump-refresh cells twice. Normally, jumping to the cell and jumping again will not be enough to reach the platform above. However, if we land back on the cell from above, we can jump from its top pixel, giving us enough height to get up.

All 4 screens on the right edge of the map are filled with bubbles, once again putting us at the mercy of cycles. This time, there aren't any walls or jump-refresh cells (except for in 8-1) to take advantage of, so we just have to wait.

In 8-2, however, is a rare case where we don't cancel out of the freeze when grabbing the leaf orb. Instead we take as much time as possible, letting the next set of bubbles rise while we hang in the air. This means that by the time we land on them, they're just enough that we can reach the clouds and get up to 8-1, skipping having to wait for the pair of bubbles on the left.

Here is a glitch that had been patched out but now reintroduced in the most recent version of the game (at the time of writing). When we hit the spikes, the game respawns us at the last location it registered us as "grounded", but that only happens if we touch the ground for a certain amount of frames. By hopping around when grabbing the spirit in 7-1, not reaching the minimum frames to count as "grounded" in the tunnel, and then dying to the spikes, we warp back to the platform in 6-1, skipping the whole return journey through the clouds.

To get up to the nook with the spirit in it, we can't take the bubble normally as we're late for the cycle, and it would bonk us against the nearby block. Wait a little to take the bubble when it's parallel with the block, and suddenly we're snapped up to the space above. Hitboxes in this game can be quite generous. That's also why we grabbed the spirit early through the corner, though it didn't save time here.

This is where Any% would finish, but we're going for more! From the last leaf to the crown, this is the single most prominent use of a dash-jump in the run. For most cases jump-then-dash is the better option, but here if we dash into the crown, the momentum will carry us further to the right upon exiting the ending animation. Instead, we want to go left to grab the last spirit, the only one that requires the double jump acquired from the crown.

After collecting all 15 spirits, we leave through the secret exit at the top of 5-1 and take the spirit elevator. The positions of the spirit bubbles here are semi-random and can cause minor time loss if they're too far apart to reach without dashing. In this case, every bubble is within reach, but for two of them (8th and 9th) dashing does let us enter them a little sooner.

I'm a newcomer when it comes to TASing so I have no doubt improvements can be found throughout the run, whether by using more advanced techniques or just from better understanding of the game's mechanics. Even when porting the movie from game version 1.2 to 1.4, I found many time saves myself, some of them from the new patch just behaving more smoothly, but some due to me being a little more experienced and thorough than when I started.

Because this game has an open map, routing changes could yield good results, whether it's switching up the screen order or pathing within big complicated screens like 7-2 or 8-1. I followed the RTA route which has gone through many iterations and seems optimal for human runs, but that doesn't necessarily mean it's optimal for TAS. It could also help taking a closer look at some of the known quirks of the game. For example, the bubble clip in 1-3 shows a way of getting out of bounds, though I've tried it in other places and, unfortunately, couldn't move when stuck in a wall.

Fellow RTA runner naan found a decent chunk of the strats used here. Special thanks also to developer Noel for creating a great game and making updates to it to help with speedrunning.