Hello bongo,

years ago, there was an App for Android and iOS, maybe this App still exists (I'm not sure).
But in general it is possible (but not very easy) to play SpaceInvasion with a Smartphone in your webbrowser.

Please have in mind, that you can turn on and off the "Desktop version" (Settings) in your mobile browser. I prefer the Desktop version while using my Smartphone, but both versions are not the optimum to play SpaceInvasion at the moment. In my opinion, this is one of the next things to work on in SpaceInvasion.
The mobile Version looks like this:

In my opinion as long as you use google chrome as the browser on your smartphone it work's quite well in Desktop version. But Opera for your SmartPhone work's even better then say firefox or Chrome. I am using Opera myself as it seems to load page's the quickest out of the browser's I have installed.

Mobile Opera Browser Download
Or
Google Chrome Browser Download

These 2 Browser are the quickest in page load for playing SpaceInvasion

I do recommend those with small screen size's to choose to play with Opera Browser as it is a good one for small screen size's.