For side mission medals: Don't get hit and destroy all enemies and buildings, even if it isn't the objective. Use the spider legs for dodgeing, the homing cluster for shoulder, and sometime spammable as the main weapon. I used big laser, but Vulcan may also work.
This game is well, it's not really fun. When I play it I go afk basically and don't have to concentrate. It's not a difficulty issue, its just not... Good. It's not bad, but medicore.
Grinding is one of the cornerstones of an RPG, along with Ultima Weapon, Ultima Weapon+, and Collect/Trade-Random-Item subquest. Also, most get a story in their somewhere.
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