I mostly play according to the intended game design. The only exceptions that come to mind at the moment are:

• Open world games (GTA, Fallouts, Elder Scroll series etc) - I tend to act like a normal, civilian part of the world. I eat and drink, travel like a person rather than player (i.e. safely, without quick travel), avoid violence and do peaceful tasks when possible. I also go on trips and take screenshots of the scenery.
  Finally, if there’s an equipment system I limit myself to “reasonable” amount of baggage (both in terms of weight and volume).
• Mirror’s Edge and Portal - the only games I learned to the point of speedrunning. I’m nowhere near the level of being able to compete with professionals (nor am I interested in that) but I can get through both pretty quickly and without issues.