Here is the full list of all 28 MeltDown achievements.
Get Level 3 Prestige
Reach 100% Critical Strike with the Fury skill.
Own all weapons.
Do a Multi-Kill.
Get Level 1 Prestige
Destroy an enemy of each type.
Destroy The Electrocutioner
Collect 100 Chips.
Max out all skills.
Destroy 30 bots with the Shocker.
Destroy 1000 bots.
Destroy The Enforcer
Destroy 30 bots with the Flamer.
Collect 5000 Coins.
Destroy 30 bots with the Grenade or Rocket Launcher.
Destroy The Barrager
Complete 10 online games.
Destroy 30 bots with the Shotgun.
Complete a mission in less than 2 minutes.
Upgrade a weapon to the maximum level.
Obtain a 3 star rank on a mission.
Pickup 10 Nukes.
Destroy 30 bots with a melee weapon.
Finish an online game with 4 players.
Finish an online game.
Complete a mission without losing any health.
Melee Kill a Fuel Bot.
Finish tutorial.