This is strange because I have run an earthquake monitoring app (originally for iPhone) on my iPad 1, and it worked very well, quite sensitively registering any movements in both the x, y AND z axis.
There are far too many limitations, of which games or utilities which cannot run, unless you buy a newer iPad or newer iPhone, because they demand iOS 6.x
Recently, I tried to install a La Cie NAS program on my old iPad, only to get the error message, only for iOS 6.x while Western Digital's similar NAS program worked well. (They are utilities to access network storage at home)
Even iBooks, which is just for reading books, has a newer version only for iOS 6.x.
La Cie replied on my complaint, that new requirements from Apple made them have to exclude iOS 5.1 users, although there still were users out there using a previous version of the app, however which users who bought their La Cie NAS after the upgrade, could not download the old version any more.
This was just an example - game producers should consider that parents often would give the oldest iPad or iPhone to their children, thus make games compatible with them. Yes iPad 1 is slower and has less RAM than the later versions, however the screen resolution is also lower (no retina) so many games should still work ok, and since iPad 1 obviously has sensors in all three axis, so that the seismic program (the name was iseismo I think) can work, it should have been possible to use the LEGO Star Wars game any way, or make some workaround, in case the gyro is different somehow.