The info text for the Steam achievement "Who Needs Tygan?" reads "Beat the final mission using only conventional gear".

What exactly does conventional gear mean in that context?

1 Answer

Apparently, coming from someone who did check in the game's files for the achievement conditions :

Of note is that this only applies to the final mission, you can happily upgrade throughout the game, just make sure your squad going into the final mission is downgraded. (Tip: Psionics/Dominate is AWESOME).

Only Tier 0 items:

  • Assault Rifle, Pistol, Shotgun, Cannon, Sniper Rifle, Sword, Gremlin Mark I, Psi Amp, Grenade Launcher
  • Nanofiber Vest
  • Medikit
  • Frag Grenade
  • Flashbang
  • Smoke Grenade
  • PCS Upgrades
  • Weapon Mods

Exceptionally, the following upgrades are allowed: (since you can't downgrade)

  • Alien/Plasma Grenade (Permanent upgrade to Frag Grenade)
  • Nano Medikit (Permanent upgrade to Medikit)
  • Smoke Bomb (Permanent upgrade to Smoke Grenade)

Forbidden Items include (not comprehensive - ANYTHING not in the list above may be bad):

  • Skulljack
  • Battle Scanner, Mindshield, Mimic Beacon
  • ANY Special Ammo (Talon, Venom, Dragon, AP, etc.)
  • ANY Special Armor (EXO Suit, Warden armor etc.)
  • ANY Special Grenade (Gas, EMP, Acid Grenade/Bomb, etc.)
  • ANY better weapon (Advanced Grenade Launcher, Arc Blade, etc.)

In essence, the game checks the inventories of all soldiers and makes sure that you only have Tier 0 items, with the exception of the three permanent upgrades (Alien Grenade, NanoMedikit, Smoke Bomb) and any drops you got throughout the mission.

Interestingly, the Nanofiber Vest is allowed as well.

Source : XCOM Reddit

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