I'd say skill issue, but it took me like 2 hours to get the true ending myself so :P
I almost got the true ending but the ambush part at the last night messed me up
oof, a tip I have is that when you get an attack speed power up it's a timed thing rather than a flat boost to your firing speed, so you should just start spamming it whenever you get one rather than trying to be accurate until it runs out
aight ill try that ill say the results later
