Alien Breed 2: Assault

Missable
There are 5 guns that have 3 upgrades each as well as the 3 item upgrades, for a total of 18. The total for all the upgrades is 111500 credits.

Please note: You must exit the Intex Terminal for the trophy to unlock.

The weapons and the first chance you will get to pick them up are...

Level 1
Pulse Rifle - You start off with this gun as default.
Shot Cannon - This is found all over all 5 levels.

Level 2
Flamethrower - This is found right next to Intex Terminal 3
Rocket Launcher - After entering the maintenance tunnels and coming back up to normal level, you will watch a short scene of a sentry turret exploding. The Rocket Launcher can be found in front of you after the scene finishes.

Level 3
Hyper Blaster - After you rendezvous with Mia you will be escorting her through the Level. Eventually you will come to a large room with a Console. You will have to defend this spot with a countdown of 1 minute while Mia accesses it. The Hyper Blaster in conveniently sitting in this room in plain sight, you won't miss it.

If you save as much money as you can in 1 play-through you still won't have enough to buy them all. Thankfully there is a little trick.

I suggest waiting until level 5 to do this to reduce the amount of separate save files that you have to make. You can only install 1 upgrade to a gun at a time. Each subsequent upgrade you buy will replace the existing one.

Follow these steps to unlock the trophy.
Step 1 - Save up as much money as you can over your play-through. You should be able to buy a few upgrades and still be able to save up a lot of money.
Step 2 - Save your game.
Step 3 - Sell off all your items for the extra credit. Buy as many upgrades as you can with what money you have. Make sure to remember which upgrades you bought.
Step 4 - Make a separate save file with what you just bought.
Step 5 - Reload the file with all your saved up cash. Purchase more upgrades that you need. Then make another separate save file.
Step 6 - Just keep repeating these steps until you have all the upgrades bought over all of your save files.