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