I've never bitten down on my tongue while playing games. Instead I push the area under my tongue forward onto my bottom teeth. It's odd because I am not 'biting my tongue' but am instead pushing the floor of my mouth on my bottom teeth.
I used to do it a lot when I was younger but as I got older I broke the habit, but I still sometimes catch myself doing it doing tense gaming moments (Last second victories, Crucial skirmishes) but am quick to stop it.
I was recently gifted Path of Exile 2, an ARPG that is a less 'run and fun' ARPG and more of a 'choose your actions wisely' type game(at least to me), and I am constantly having to stop myself from pushing the bottom of my mouth onto my teeth.
The game isn't high stakes, unless there is an attempt at a leaderboard ranking or the character is 'Hardcore', but there is so much happening on my screen that after almost every mob encounter I have to relax my mouth because somewhere during the frenzy I would begin my potentially harmful habit, I've actually gotten sores on the bottom of my mouth caused by my teeth slowly pressing more and more in that area.
Needless to say, I did not survive the encounter.
I realize now that this bad habit occurs most frequently at my current gaming age whenever I play an ARPG title (Diablo 2 & 3, Titan Quest, PoE1, W40k Martyr, Last Epoch).
Being surrounded by enemies while fire rings threaten to kill me? This is fine!
Maybe it's because of all the things to worry about and keep track of, the close/isometric camera angle, moving amongst enemies without getting cornered, doing combat and avoiding projectiles/attacks, looking at my health and resource bar, keeping track of cool downs and damage numbers, It's all happening on one screen together at the same time with short breaks in-between the next wave of enemies.
Sensory overload is probably the answer and I instinctively revert to this coping mechanism to keep myself steady and process what is happening and what to do next to survive.
I should probably switch to playing something less intense... But it is fun to play!