This is an ancient game made for the unity web player, and thus has to be opened with Internet Explorer 11 or the like.
As IE11 is soon being discontinued you can also play it with MS Edge, but you will have to turn on IE mode.
Though soon enough that might not exist either and other options will have to be utilized. 

To actually run the game, download the "Space Rollers - game" folder and run "index.html" in the aforementioned programs. 

Note that the game was published with the 4-th level having a bug where it is impossible to actually proceed to the 5-th level,
making the game unfinishable, not to mention the fact that the 4-th level is ridiculously hard. 
The unity project files have been long lost and I can't seem to turn the GAME.unity3d file into a unity project (for now) so the bug remains.