alright when raiden and vamp are dueling, and when the gekkos come how do i beat them? they explode and when they do, mission failed, any tips

You have to use the rail gun you got from crying wolf and keep shooting them in the head... use your solid eye to see were there weak spots are.

use the rail gun and go to first person mode. MAKE SURE THE RAIL GUN FULLY CHARGES BEFORE YOU SHOOT IT

how do i fully charge it?

Just use the rail gun and keep shooting the top of the gekko's, their main mechanical bit. Tis what i kept doing.

To charge it, just ready your gun and it'll charge. If you go into FP mode, you can see it charge up with a bar. I didnt have to let it charge, I just fired like mad :D

 Just wait. In FPS mode you'll see it charge. Level 3 means it's fully charged.

You hear a little beep when its fully charged. This will take them out in one shot rather than a few/many. Just wait for the beep and BLAM.

If you look in the corner under your weapon icon there is a bar that charges, but you have to hold down L1 to get it to start charging. If you are in first person mode the bar is in the middle of the screen. Buy ammo for it from drebin (just press start, go into weapon, highlight the rail gun and press triangle), you will probably need it.

As for strategy, you can either go straight for the head, or shoot them in the leg to make them collapse first. I did a bit of both depending on how many I was fighting. Also very important is sniping them before they get to your area. Right at the end, if you haven't been sniping, you'll get like four of them all at once in your area about to explode. I died a few times at that same point each time. But you should have moments where there aren't any in your area, but are some walking around and shooting while standing in the distance. Go into FP mode with the rail gun, and use your solid eye to snipe them. Thin out the herd, so they won't all gang up on you at once.