Butterfly (final) starts in fullscreen mode, so I get black screen and doesn't accept Alt+Return,
so here is a patch to "see something"

In BufferflyGame.cs, at line 75

replace

graphics.PreferredBackBufferWidth = 1024;
graphics.PreferredBackBufferHeight = 768;
graphics.SynchronizeWithVerticalRetrace = false;
graphics.PreferMultiSampling = false;
this.IsFixedTimeStep = false;
this.Window.AllowUserResizing = true;
this.graphics.IsFullScreen = true;
graphics.ApplyChanges();

with

graphics.PreferredBackBufferWidth = 800;
graphics.PreferredBackBufferHeight = 600;
graphics.SynchronizeWithVerticalRetrace = false;
graphics.PreferMultiSampling = false;
this.IsFixedTimeStep = false;
this.Window.AllowUserResizing = true;
this.graphics.IsFullScreen = false; //now is false
graphics.ApplyChanges();


There are other issues to fix it seems. Stay tuned.

Strange keyboard mapping in first menu seems to be :
Y:Up (credits)
A:Down (start game, or continue game?)

There is a out of range error that prevents game from starting. Here is the fix :

In GameLogic.cs, at line 232, replace


if (playerData.CurrentLevel > levelList.levels.Count)
playerData.CurrentLevel = 1;

with


if (playerData.CurrentLevel < 1)
playerData.CurrentLevel = 1;
if (playerData.CurrentLevel > levelList.levels.Count)
playerData.CurrentLevel = 1;

Now we can see the little butterfly in 3D.

Arrow keys allow to turn butterfly
Space make it use its wings to ascend
Mouse wheel acts as a zoom
QZSD turns camera