Flutter

About the game

At Lepidoptech Research Labs they bred caterpillars and butterflies to extract a drug nicknamed "the butterfly effect". Then something went horribly wrong. Now the corridors are crawling with mutated insects, and you are a lab technician with a gun and a long way to go to the exit.

Flutter is a run-and-gun game with a twist on the controls: you move with the keys and aim with the mouse, anywhere on the screen, so you can run one way and shoot the other. The corridor scrolls sideways, caterpillars crawl on the floor, butterflies swoop in from above, and what you shoot leaves splats on the walls in the colour of the creature. Health packs and weapon upgrades lie along the way. At the end of the lab waits the biggest insect of all.

It is a short game with a title page, a story told in three picture slides and a game over screen that lets you click to try again. Everything here, from the art to the music, was made by one person in a week.

Playing it here

The first time you click Play the page downloads the Python runtime and the pygame library (about 23 MB), which takes a few seconds; after that a "click to start" message appears, and one more click starts the game with sound. The download is kept by your browser, so every other pygame game on the site opens faster. Nothing is loaded from other sites. The game has no save.

Controls

Tips

Keep moving. Standing still is how the swooping butterflies get you. Strafe and shoot at the same time.

Pick up the packs. Health packs and weapon upgrades appear as you go, so do not run past them.

Arrive in good shape. The last insect is much tougher than the rest, so do not waste health packs on the way.

Frequently asked questions

Does it save my progress? No. A run starts from the beginning.

Does it work on a phone? It needs a keyboard and a mouse, so it is meant for a computer.

Why does the first start take a while? The page loads Python and the game libraries. Your browser keeps them, so the next visit starts much faster.

Is it free? Yes. The game's code, art and music are dedicated to the public domain (CC0).

Credits and licence

Flutter was made by mit-mit for PyWeek 29 in 2019, on the theme "The Butterfly Effect": game design, programming, artwork and music. The code and artwork are CC0. Two sounds come from freesound.org and OpenGameArt and are CC0: "Wet Splat" by JustInvoke and "Squeaky Rat" by qubodup. All the lettering in the original is baked into pictures and was typeset in "Mechfire" by Pixel Sagas, which is only described as freeware, so for this site all of it (the title, the story slides, game over and continue, the control hints, the pick-up labels, the boss label and the door numbers) was redrawn with Press Start 2P, Copyright 2012 The Press Start 2P Project Authors, under the SIL Open Font License 1.1. The version served here changes only the main loop (the browser needs it to be asynchronous) and those pictures; the change, the original zip and the redrawn images' script are linked from the Licenses page. The game runs on pygame-ce (LGPL-2.1) and CPython, whose licences and source are also linked from the Licenses page.