(note: TLDR summary near the bottom of this post

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First of all - an introduction. I heard about this game about a week ago on gametrailers, when I was just randomly browsing, and I saw a vid of someone doing Through Fire and Flames in this game. So I then decided to look for it, and I found out that it kinda only works on weekends. So I signed up for the beta, and completely forgot about it this week. Only by randomly checking my email on Sunday evening I noticed the game there.
This is what I think could be done to improve the game, from my 4 hour play experience. ^^
First thing I noticed is that there is no "Preview Song" button or something like that. I had to alt+tab out to browse through my songs and find one that could sound good. And that wouldn't be such a bad thing, but the ingame music keeps on playing even after alt+tabbing, thus not letting me preview my song properly. I have found a workaround for that - if you select the Audiosurf Radio tab before alt tabbing, it will stop the music. So here comes the suggestion (or some of its' variations):
1. Make clicking the song (or certain other menu options) just select it (displaying useful info), and clicking it again will start the loading. Now the preview could come in 2 varieties:
a) After clicking the song, a button (that's normally grayed out) flashes up, and you can click it to play the song.
b) After clicking the song, it will start previewing automatically after a second or two.
2. Leave the song selecting as it is right now, but make the 2nd mouse button be the preview key, and just hovering over the song will pop up a small info box.
3. Make the game stop any sound playback upon alt+tabbing, so you can preview your songs in Winamp, WMP or what have you. (Not recommended lol

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Right, now with that out of the way we can get to some other usage of the 2nd button! First my suggestion would be to remove the Dual ships, and making every character have a 2player mode. They can be re-implemented in the following ways:
1. When you click your character, a dialog box pops up with an expanded description of the character, his abilities, etc. And for the dual mode:
a) On the dialog box there could be 2 buttons: 1player and 2player (could be named in a fancier way), and you can clicky them to select. (there could be some extra options too)
b) Once the dialog box pops up, you can either click the 1st mouse button on it for 1player, or click the 2nd mouse button for a 2player game.
2. Leave the selecting as it is now, and make the 2nd mouse button toggle between 1player and 2player modes.
You probably noticed that both suggestions are just about the same thing. That's because I thought up the 2nd one while writing the 1st one

. And I thought up some achievements and score multiplier thingies too:
Colorblind (I thought it up for Mono, but could work for all chars): Hit 95% of all cube thingies.
Stacker (all chars probably): Overfill a column with cube thingies 15-25 times in 1 song. (achievement)
Starburst: Hit 95% of non-grey cubes as Mono or finish a song without overfilling as any other character. (achievement, but could work as a multiplier)
Those may need some polish though. I had actually thought of another idea while I was writing the achievements, but I forgot what it was, so bleh.
And a summary for the TLDR crowd:
1) Add a song preview option
2) Remove the one 2 player character and make all characters have a 2 player option.
3) Achievements
Many thanks for making such a great game and sharing it with us on weekends. ^^
Wall of text crits you for over 9000.
