Overgaming, in PUA, is when men try so hard to not seem needy or desperate that they go too far in the other direction.
The original concept of overgaming was that it would be, for example, overgaming to neg 6/10 girls. The idea behind the neg is to stand out by being the one guy who makes a backhanded compliment to a 9/10 rather than worshiping her; but if the 6/10 is already used to being insulted based on her looks, she wouldn't take the neg the same way a 9/10 might.
This logic might not apply in the case of a modern 6/10 girl who has received significant amounts of attention and validation via social media, to the point that her ego has become inflated; but it could still apply in rare cases to a more sheltered girl who has not had the experience of having a lot of orbiters.
In incel Discord servers that allow femoids, one will often see men calling 6/10 girls "cunts" and such, in their eagerness to not seem like beta orbiters.