So, shall i buy this game?

Small but extremely active with the Diplomacy Expansion only. I can usually play 2-3 4v4 or 5v5 games a night if I wanted.

The only digital download I know of is through Impulse which I would highly recommend anyway if you want to play online and stay updated.

You might be able to find box sets of Trinity, but it seems some have had issues with registering the key (possibly repacked games, etc).

I saw in wal-mart the original base game for $10 if you just wanted to play around until Rebellion comes out.

So in summary

• Buying Trinity outside of impulse may be risky for registration but could save you some money.
• Trinity (Impulse) = $40
• Trinity + Rebellion (Impulse + pre-order) = $70 ($10 saving for owning Trinity or Diplomacy)
• Rebellion (Standalone preorder or wait) = $40 (or $30 if you own Trinity or Diplomacy)
• Sins of a Solar Empire (Walmart if available) = $10 (no expansions)
• Expansions (available via Impulse) = $10 each for Entrenchment and Diplomacy

The community is small in Demigod, but still active. 

Stardock puts the game on sale from time to time.  The only place you can get it digitally is through the impulse store.  You can likely get it on the cheap on amazon, though. 

It looks like the OP was posting from the Demigod forums, and Off-topic is shared between all of them. No idea on the status of Demigod, but I would say "probably not good".

Good point... Didn't notice that.

Edit - He should buy Soase if he doesn't have it anyway