1. Clothing, that includes a layering system for what ever wheather I find on the other side, drop what I don't need on arival
2. Rat 7 knife, and a saw or hatchet & Leatherman Supertool, or Rebar.
3. Shelter of some kind, heavy poncho or small trail tarp & reusable space blanket
4. Fire kit in waterproof container (Numyth Talos, Fero, Jute, Charcloth, and some Trioxane Tablets)
5. Firearm, What one would be tough with no idea what you were heading into, 12ga 870 might be a safe choice with mix of shells, or a .22 and carry more ammo? toss up.
6. Stainless steel water bottle and cup, Possibly a small MSR Seagull with that. (for boiling water if theres no water there I'm dead anyway)
7. Headlamp Fenix HL30 and several lithium batteries
8. mix of cordage
9. A couple of conibear traps, 110 and a 160? mabye a small fishing kit. (hopeing its similar to earth if not theres no way to know how prepair a kit)
10 Large dry bag, to keep gear dry and usefull as a flotation device.) (if you were smart you might start off with that full of air and tied to your pack incase you were droped in water.)
11. bandana, or similar item to filter the air a bit from dust or smoke.
12. Photo of wife and daughter, to keep me pushing forward.
13. Pack to put it all in, Large ALICE and stuff any remaining space with some food and other gear, shed weight as needed once I arrived.