Great Race of Yith (New)

In prehistoric Australia, the technologically advanced Yithians were attacked by the Flying Polyps. In order to escape, the Yithians transferred their minds far into the future. Unheroically, they traded places with a race of hive-minded insects, leaving them (undoubtedly confused) in the Yithians' old bodies in the midst of the Flying Polyp war, never to be heard of again.

In the RPG...

Each member of the New Great Race is actually composed of around 500 insects, controlled as a hive-mind and working in unison. Each individual insect has a single hit-point, which means that even an "average" member essentially has 500 hit-points. The Malleus Monstrorum states that the hive-mind collapses when 75% of the insects are destroyed, but even with that stipulation, it means the equivalent of 375 hit-points. While this seems impressive at first glance, it is only really relevant to gunplay. A single bullet would only take out a few insects at a time, so you could never realistically fight the New Great Race with guns, but any explosive, however, would hit every insect within the blast radius, taking their 1 hit-point even if they were at the very edge of its effective area. In game-terms, this means the New Great Race are invulnerable to all melee weapons and guns, while not even being worth a damage roll for a successful explosive attack. They're essentially a binary opponent—all or nothing.

    The 7e Malleus Monstrorum hasn't so much changed stats here, but added them. The old edition only gave STR, CON, and SIZ for the individual insects, whereas the 7e edition has now given stats for the swarm. INT has changed though, but only in range. It's average has remained the same.

In a video game...

I can't say I'm really up on the technical limitations of modern GPUs or CPUs, but I have a feeling they would struggle with even a small specimen of the New Great Race. 500 individual insect models moving in real-time seems like it might seriously kill your frame-rate. Even if it could be done, should it? An enemy that can't be shot, yet is killed with a single grenade, doesn't really sound like it would be worth the effort to me.

In a film...

Something similar to the New Great Race has already graced the big screen. In the film Constantine, there was a demon that was composed of various bugs, worms, snakes, etc. I remember thinking it was very cool at the time. While the New Great Race don't necessarily take human form, I would presume they could, which would look great on-screen, especially with the jump in CG quality since Constantine come out. What would add a nice touch is that it's mentioned in the Malleus Monstrorum that the insects shimmer with a spectrum of colours when they fly, which I think would also work with any rapid shifting of their mass. Unlike a game, where the player may or may not have a grenade handy, it's easy for a screenwriter to have the protagonists without such a weapon, making the New Great Race a much scarier adversary.