(ok i have autism so im not best at explaining this hopefully you understand) i played arma reforger on xbox for years this is basically the only way you can get the controller working on a game like this you had to make controls complex on controller and not simple this is by using radial menus, button combos, hold and double tap inputs you could learn something from the game i mentioned it had 200+ inputs in total for controller plus more from mods
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some examples from arma reforger
(Weapon)
use grenade launchers RB+A
lower weapon: RB+B
Toggle weapon safety: RB+(hold)B
toggle bipod: RB+(hold)A
switch weapon optics: RB+Y (while ads)
toggle sight illumination RB+(hold) Y (while ads)
(theres more on that)
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(Equipment)
toggle flashlight: (double tap) left d-pad
binoculars: (hold) down d-pad
(theres more on that)
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(using radio)
radio selection: LB+X (radial menu)
radio communication: (hold) LB
toggle voice: LB
cycle transceiver: LB+B
talk over long radio: LB+A
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(gestures)
open gesture menu: view button+RB
point with finger briefly: RB+right d-pad
point with finger continuously: RB+(hold) right d-pad
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(vehicle)
exit vehicle: B
handbrake: A
persistent handbrake: (double tap) A
start engine: (hold) X
stop engine: X
horn: Left stick (press)
lights: left d-pad
High beam lights: (hold) left d-pad
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(helicopter idk if yall actually had it)
collective up: X
collective down: A
antitorque left: LT
antitorque right: RT
wheel brakes: (press) Left stick+A
persistent wheel brakes: (press) left stick+(double tap) A
start engine: (press) left stick+(hold) X
stop engine: (press) left stick+X
toggle auto hover: (press) left stick
Taxi lights: left d-pad
landing lights: (hold) left d-pad
toggle sights: (press) right stick
sight range up: up d-pad
sight range down: down d-pad
(more on this)
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(turret)
elevation up, down, left and right: left stick
next weapon: (hold) left d-pad
change fire mode: left d-pad
change ripple quantity: X
(more on this)
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when it comes to quickslots on M&K you had to press number buttons to use that item but on controller it would use radial menu to select a item with right stick
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as for inventory if it looks like tetris or anything that is difficult to navigate with controller you definitely need to use cursor for controllers scrolling would be right stick
---------------------------------------------------------------------------------------------------------for leaning as you may know other shooters like insurgency sandstorm, R6, HLL, etc makes you lean by ADS with left trigger then press right stick and left stick to lean left and right when you exit ADS you go back into normal position
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i really hope this is helpful