I'm a trainer, so I compiled a lot of information into relative short message. There's lots of information on these subjects, but the main issues to look up are "upper crossed syndrome", "lower crossed syndrome", or "anterior pelvic tilt". You'll need to foam roll, stretch, and strength train depending on the exact issues that you're facing.

I said the same thing. Stretching can help but it's only part of the solution. Gaming posture can lead to Upper-crossed syndrome (rounded forward shoulders, kyphosis, a hunched back, lack of t-spine mobility, tech neck, etc.) and lower crossed syndrom (weak core, tight hips, weak glutes, anterior pelvic tilt). To correct this you'll need to do 3 things 1 - strengthen the weakened muscles 2 - stretch the tight muscles 3 - change the habits that led to the issues Stretching by itself could lead to more issues, if you're stretching muscles that are already lengthened due to improper muscle length tension relationships and NO corrective work, will override continuing with poor daily posture.

Poor posture when sitting.