There are benefits from paying but none of them are necessary to compete. The only real necessity to compete is to be in a decent alliance, not being in an alliance is basically a death sentence. That said I don't really have time during the day any more to check on attacks and such so I can't really play it. It's definitely enjoyable but it will absolutely destroy your sleeping patterns if you play it properly.
It's similar in the fact it runs in real time and is space based. It's more combat orientated from what I tried of ogame and personally I found it a lot more engaging and polished. The game runs in rounds of usually around 7 weeks and each round has different ship stats so becomes a slightly different game each time.
