Other than the Force Gun, being able to use your Stasis effectively is what will really help, and if it's maxed out, you'll rarely not have at least one charge up. If I started to run low on Force Gun ammo, I'd save shots for the fast crawler necros or necros that ran and leaped at you, and I'd used stasis and rivet gun more until more ammo came in. That said, if running low on Force Gun ammo, switch to other guns and hope the enemies drop some ammo every so often. credit to lukey52 for the collectables guideĪs an addendum, after waves three and six (out of ten), you'll get a slot-machine prompt to add a third and fourth weapon to your arsenal during that challenge run, which, unfortunately, you'll start receiving ammo for them, when you want to keep your Force Gun fed. In the case you run out of Force Gun ammo, use charged alternate fire from the Rivet gun until you find more (normal difficulty tends to be the most generous when it comes to this).

Just make sure that you always keep an eye out for ammo and boxes some times hidden in the background of the maps.

Lastly, the spitters can most easily be taken down by throwing their projectiles back at them using Kinesis (technically this can be done to the Lurkers too but personally, I didn't find it as effective). Immediately shoot it a second time to kill all the swarmers and then shoot it a last time to kill the pregnant necromorph off ( you can just shoot its legs out to avoid the swarmers but I believe you get 250 points per swarmer killed by doing it this way) For Lurkers (the little 4 legged necromorphs that shoot from their 3 tentacles), a fully charged secondary shot from the Rivet Gun will be enough to one hit kill it. You may want to keep a slight bit more distance between you and the pregnant necromorphs during the first shot due to the swarmers that charge out. The enhanced necromorphs (dark complexion versions of the slashers and leapers) take 2 close hits from the Force Gun to kill. This will ensure that you get the maximum amount of points per kill as it causes most of the necromorphs body parts to fly off in a single hit. Then start the challenges on normal (higher difficulty levels do not impact your points), let most enemies get as close a possible to you without attacking and spam the Force Gun primary fire. The best strategy to approaching all of them is to first complete the campaign portion of the game with all upgrades for at least the Force Gun and Rivet Gun found. All of the challenge related trophies are A LOT easier than they appear to be.

Dead space extraction bridge