Personaly i dont like the orginal space invaders game, but i thought i would give SIIG a chance, so i downloaded it today. I think this sums up my opinion of it. I think i have rsi on my eyeballs <3
I loove the retro feel of SIIG and I've played it all the way through. Now I'm just trying to see how many more 'evolutions' I can unlock. Remember, even after you've beaten the primary stages, there are extra stages, weapons and goodies you can unlock by filling your Gene gauge several times more. I haven't encountered a threshold yet and I've unlocked 8 special stages. I jumped on SIIG the moment it came out and I haven't regretted it since. I do wish Stage 0 lasted longer. :]
The games music mode gives it awsome replay value. Count every song you have on your iPod, that is how many extra levels you have.