Butterfly Effect is a 1.9 Medium Demon created by Linco. It is an easy remake of Nine Circles by Zobros. Linco started to create the level at the time of The Realistic (late April), but he published it in mid-summer. Due to its unusual name, it was known and got rated several months later. It is considered an easy demon and test the player's basic ability to control their wave and respond as fast as possible to incoming obstacles.
The level is a Nine Circles remake. It is much easier than the original Nine Circles and utilizes a teal-like color scheme similar to Astronaut 13 by Dzeser. It is one of the easier Nine Circles levels created, and features many mini wave segments utilizing fakes in quite a few places. It has few gravity changes. The level is good for players wanting to get better at the wave or Nine Circles levels overall.
The level starts with a moderately confusing cube section that features several fake lines and trick jump rings to try and throw off the player. Next, the player enters a double speed ship sequence, which is fairly easy since the second half of this ship sequence can be played off as nearly auto. Afterwards, the player enters a short auto cube section where the music will rapidly drop and pick up speed. Then, the Nine Circles wave is introduced. This wave features many fake lines and size changers, with many saw-blades and spikes in an attempt to intimidate the player. The first half of this wave segment is mostly in regular size and is in regular gravity. However, in the second half, the wave will gradually increase in difficulty, and will start throwing size changers and brief spam segments with tighter spaces and tricky mini wave segments. Then appears a long but very easy corridor with shattered saw-blades and another mini wave segment. Near the end, a wave dual with mixed sizes will appear it is the trickiest part of the wave. If the player manages to pass this, he or she will have to survive one last small stretch of triple speed wave before encountering a half speed portal, from which the level is practically finished. The creator's name "LINCO" can be seen at the bottom, and after a short half speed easy spam segment, the level ends.
- Roby GD crashed at 96% twice.
- Milesman34 crashed at 89% and twice at 90%.
- Crispy Dash crashed at 89%.
- DemonThunder crashed at 93% and 96% twice.
- Freakify crashed at 91% eleven times.
- This is considered one of the easiest Nine Circles levels ever. Its difficulty can be compared to Fractured Circles.
- This is the only level, alongside The Realistic, to feature "spearhead" gears instead of "Blast Processing" ones in the ship sequence.
- This is the only level, alongside Crimson Clutter and Beautiful Eyes to reverse the order of flashing lights (4-3-2-1).
- This is one of the few levels to have a title that is not inspired by the name of the song used and/or without the word "Circles" in it.
- This is the unique level that uses introflexed clusters of spikes to decorate the slopes.
- In real life, the "butterfly effect" is the phenomenon whereby a minute localized change in a complex system can have large effects elsewhere.
- The level is a copy of itself.
- This is the first Rated Nine Circles level to not have a NK song (Viewtifulday - My Future)