A circle named O was minding her own business, when suddenly she came across an evil wizard, who was a triangle. The wizard saw the circle, and saw that she had only one side. The wizard disliked that the circle had only one side, so he cast an evil curse on the circle, confining her to a one-sided surface, a Möbius strip. The circle tried as hard as she could to escape, but every time she got free, she ended up on another Möbius strip.
Eventually, she broke free, only to find herself in an infinitely-long plane. However, the wizard found her and painted a question mark on her? This made her confused? Why was there a question mark on her? Just then, she noticed where she was? She was at the end of a level, and she looked just like a goal orb? And a speedrunner was headed her way, trying to collect her‽ She tried moving around, only to find out she couldn't? Fortunately, she could still jump? How far can she get before the hero catches her?
The goal is to get as far along in the level as you can without getting caught by the speedrunner, using downwards slopes to gain speed. Your score, shown in the upper-left corner of the screen, is the distance you've gone, in pixels (at the default size). There's no ending; the game will continue as long as you survive. See how high of a score you can get.
Press P, escape, or enter to pause the game. Press M to mute or unmute. Every other key* does the same thing. If you're using a touch device, you can also do that same thing by tapping anywhere within the game.
Press a key while on the ground to jump. Hold the key longer to jump higher.
If you're holding a key when you land, you'll bounce. Bouncing on a downward slope can cause you to quickly gain speed (though often at awkward angles), but be careful, since bouncing on an upward slope can cause you to go backwards!
If you have a power-up, press a key in midair to use it. Power-ups are described in the next section.
* There are a few keys that won't work, like F1-F12, Tab, and anything reserved by the operating system. Also, on Mac OS (at least in some versions/browsers), Caps Lock doesn't work correctly.
There are many power-ups floating in midair. Touch one to pick it up, and press a key to use it. If you touch a power-up while you already have a power-up, you'll lose the power-up you already have. Generally, power-ups can only be used once.
Speed booster: Press a key in midair to immediately increase your speed. This will add to whatever speed you already have.
Double jump: Press a key in midair to jump again. Like with a normal jump, you can hold the key longer to go higher. Only gives one jump.
Shield: Gives temporary invulnerability for five seconds after you pick up the power-up (not after you use it). If the speedrunner hits you while you have this power-up, then they'll be knocked backwards. If you press a key in midair before the five seconds are up, then the speedrunner will immediately get knocked backwards, regardless of where they are, but you'll lose the invulnerability. In either case, the speedrunner will get knocked back farther if they're on an upward slope.
Wings: Lets you fly for five seconds. Press a key repeatedly to gain height. Unlike the shield, the timer starts when you press a key in midair, not when you first collect the power-up.
Bubble shield: Press a key in midair to quickly descend. You can use this to bounce off of a downward slope and get speed, or if you release the key fast enough, you can start rolling down the slope.
Parachute: Press an hold a key in midair to slow your descent, but as a downside, it also slows your horizontal speed. Once you use it once, you can use it again as much as you want until you hit the ground.
Click "Options?" on the title screen or pause screen to get to the options menu.
Audio: Change audio settings. (Note: Stereo audio is not currently available; that setting exists because I copied it from earlier games I made that did have stereo audio.)
Inline/Fill window/Full screen: "Inline" displays the game and the description; "Fill window" hides everything else and attempts to fill the window; "Full screen" makes it full screen. Some of these options might be unavailable depending on your browser and which site you're using to view the game. You can exit full screen mode by pressing Escape, or going back to the options menu and choosing Inline. This option is not saved.
Black and White: Switch the color palette to black-and-white mode, which is higher contrast than the default palette.
Assist options?: Display a menu of options for making the game easier
Invincible: Allows you to continue playing once the speedrunner hits you. However, you will stop gaining points, so this isn't that helpful in getting a high score.
Game speed: Slows down (or speeds up) the game.
Disable walls: Gets rid of the short walls that normally appear every so often that you'd normally have to jump over.
Show jump arcs: Shows the trajectory your jump will have if you jump. While in midair, shows both the trajectory for a maximum-height jump and for if you let go of the jump button immediately, and in some cases, the trajectory you'll get if you use a power-up.
Change all power-ups to?: Select a power-up to change all power-ups to that power-up.
Don't save high scores: If this is selected, high scores won't be saved, and you'll keep whatever your current high score is even if you get something better.
Reset high score: Deletes your high score.
Tips and tricks
Roll down steep downwards slopes to gain speed.
Landing on a downward from a jump slope will give you lots of horizontal momentum. Landing on an upward slope will kill your momentum.
You can't go backwards just by rolling down a steep slope, but you can go backwards if you bounce off of something. If you ever find yourself going backwards, jumping will cause you to start going forwards again. You don't lose points while going backwards, but you don't gain any points until you get back to where you were.
Unless you have black-and-white enabled, the color of the screen shows how close the speedrunner is to you. You can also see this by looking at the top of the screen; the vertical line indicates the speedrunner's position, and the dot indicates yours.
Walls are actually infinitesimally tall. If you're in the air at all, you won't hit them.