Well at least I wasn't the only one that was messed up with an intro mission. That makes me feel better. I hate it when I suffer from PEBCAC. It's embarrassing.
Cheevos are very easy in this game done single player on heroic and loved it, just started my legendry solo playthrough stated off on the 9th level going to do the last 2 which are the hardest first then the rest should be cake I hope!
Spoiler alert
The big firefight battle at the end is going to be messy on legendry.
I found a Glitch on the last part of the game, here's what to do when u have to use the big mac cannon to take ot the huge ship u have lots of dropships and banshees to take out. Jump out of the cannon don't bother shooting them go back behind and hide until u are told to hit the middle red core then jump back in and just shot it game over.
This will make it very easy on legendry because on heroic it took me 2/3 attempts hope ths helps somebody.
Tip for quickest way of ranking up go into score attack game it's single player score attack on heroic it's the standard setting veto until u get corvette map pick snipers game u have unlimited ammo stay in the tunnel of the safe room snipe out I got that cheevo first try for get over 15.000 points u can get about 1700/1800 credits per game in about 10mins if that's to hard for you just do the same with gruntapocalypse on the same level easy kills easy points u actually can get to the highest rank without ever playing multiplayer matches!