I'm using an iPad 2. Running the most current iOS system update. And I believe I have the most up-to-date version of the game. The only thing is, I haven't yet completed the primary campaign. I have 2 missions remaining (last alien and last predator missions). Also, I'm not sure if this makes a difference or not by I'm playing on normal difficulty...
... Speaking of which, is there a way I can change the difficulty to hard without starting a whole new player profile? I'm not seeing an option anywhere to do that....
Anyway, none of the side missions have unlocked for me yet, but it's giving me the option to buy them for $2. It's not very descriptive though... I dunno if it's $2 per mission or $2 total for all missions. Plus, I mean, why pay for it if they'll unlock once I complete the primary campaign, right? I'm just not sure what to do. Lol. Right now I'm just building up my characters though... I pretty much played through the whole campaign using virtually only the starting items/weapons/characteristics, and the final alien mission/boss is proving to be impossible without upgrading to stronger armory/abilities. I DID unlock the two bonus missions for finding all of the secret items though...