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