Can you still play PSO Episode I & II on Xbox?

I heard that you need a Xbox Live account to play Phantasy Star Online Episode I & II on Xbox, even for the offline mode.

Unfortunately, the service was shut down for the first Xbox generation (in 2010-04-15).

I wonder:

• Is it impossible to play this game on the Xbox 1 now?
• Or do those versions that were once activated in Xbox Live still work?
• If so, are they bound to the Xbox they were activated on or could you buy an once activated version of PSO Ep. 1 & 2 and play it on your Xbox (which was never connected to Xbox Live)?
• Back then, was it sufficient to activate the game once, or would you have to subscribe to the service for as long as you wanted to play? (difference between online and offline mode?)

(I assume you can't play it on Xbox 360, as it is not listed in the List of Xbox games compatible with Xbox 360.)