Install a modification of each category on a single weapon.

Name the locomotive.

Patch the Gasmask.

Finish "Power plant" quest

Engage in all optional conversations

Use bricks or bottles to lure an infected into attacking a human

Win the water gun fight

Play the Jak X game in Left Behind

Win the brick throwing contest

Collect all comics

Break into every locked door using shivs

Find all training manuals

Upgrade and then break one of every melee weapon