- I died
- I have died
which one should be used the moment after dying in a game?
In most cases, the choice of a perfect or non-perfect construction is a free one, depending on precisely how the speaker is viewing the events temporally.
"I have died" says that there is a present consequence of the event, whereas "I died" does not: it does not say that there isn't a present consequence, merely that the speaker is choosing to focus on the completed event, rather than on its consequences.
"I died" is common, or even more so, "I'm dead". Related example:
Oh no! I dropped my ice cream!
"I have died" is grammatically correct, and might be more appropriate, but it sounds a bit too formal to use in such a casual context. For whatever reason, the perfect tense adds distance between you and the event, as if you are casually remarking on it rather than experiencing it. Related example:
Oh dear. A tiger has bitten off my leg. What a bother!
Relevant Monty Python (warning: strong language, graphic violence)