Behold, the power of potatoes!
No, really. Just beat Ironman Mode in Mothergunship: Forge, mostly by virtue of a pair of potato cannons.
In Ironman Mode you have 1 HP and no starting bonus. Get hit once and you're done for. Well, I nabbed some armor along the way, but still didn't get hit so the safety net wasn't needed.
Started with a crappy Rapid Blaster that carried me through the first few levels, then I got a Pizza Launcher that helped me through a few more... and a Potato Cannon just before the first boss, and he dropped an item that guaranteed a Legendary item in every Treasure Room and Shop. I grabbed a key and opened a Treasure Room with it... where I found an Epic Potato Cannon (all my other weapons were common) and... the Multishot Legendary. +1 projectiles and a bit of additional spread to all guns. My two potato cannons were aligned to hit practically the same spot, and...
Despite the silly name, the Potato Cannon does the "Max" damage base of 500- I think there's one weapon that does more, but it's super rare, and possibly the Omega weapon I see on the list but haven't unlocked yet. But on top of that, the 'potato' fragments on hit, dealing more damage if the first hit didn't take out the target. With four potatoes hitting the same target, and four sets of fragments... it was a killer combo.
Even those laser bastards went down in like three volleys, and they usually take the better part of thirty seconds even if your DPS is pretty good. The Dragon Boss lost half his health in his first appearance, and only took so long to kill because I pushed him to his third phase before the second phase's Add Summon was over so the third phase's group showed up right after to annoy me.
That's Full Metal Completionist down with Ironman Mode taken care of, I only have the Speedrun (20 minutes in the base mode, failed by 46 seconds on my first attempt) and Gun Collector (get all the parts... luck) and I'll have all the achivements I can get...
...Unless somebody here has a headset and a copy? There's a bunch of co-op achievements too.