New loot on every floor
Floors now hide valuables you can bring back to the surface. Load them into the truck in the yard to sell them. You get paid for finds even if the contract fails, and deeper floors pay more.
Folders, Hard Drives & Laptops: small finds that fit in a quick slot.
Server units: heavy, two-handed, and packed with data.
Anomalous artifacts: strange objects that are dangerous to carry and worth a lot (more below).
Technology now has to be unlocked
New gear no longer just shows up in the shop. Mines, the Sound Cannon, the Foam Gun and every Tier II suit chip are locked behind blueprints, and you find blueprints in the data you recover:
a Folder unlocks a gadget
a Hard Drive unlocks a chip
a Laptop unlocks either one
a Server unlocks two
Blueprints stay unlocked for the rest of your campaign. A new campaign starts with everything locked again, so every run is a climb back up the tech tree. Items that still need a blueprint show in the shop as dark "NEEDS A BLUEPRINT" cards, so you always know what you're hunting for.
Suit chips now have tiers
Every chip is now Tier I or Tier II, and the tier is shown on the chip. You need Tier I installed before you can install Tier II.
Artifacts
Resonance Crystal: it reacts to voices. Whispering around it is fine. Talking makes it crack, and shouting shatters it in seconds, and a cracked crystal is worth less. Its ringing also draws creatures. Getting one home means the whole crew has to keep quiet.
Pulsar: it sends out a sound pulse every few seconds, and the pulse lights up the room around it. That makes it a free light source, and also a beacon that tells every creature on the floor where you are.
Flasks: acid and ice
Sample Flask: set it down gently and it's fine. If you throw it, kick it, drop it when you get knocked down, or catch it in a blast, it shatters into a pool of acid. The acid is lethal to players and eats through creatures, and even the unkillable ones eventually give in. A fragile piece of loot is now also a weapon.
Cryo Flask: stored in freezer cabinets locked by tone or melody locks, so you'll need to sing them open or break them open. Carrying it slowly freezes you, so don't hold it too long. If it breaks, it freezes everything nearby solid, players and creatures alike. A frozen body is a statue: a kick or a hit shatters it, and it can't be revived.
Find it, carry it, don't drop it, and keep your voice down.