Titanfall: All My Pilots Are Players

[Fourth-Dimensional Disaster + Titanfall + Dual Transmigration]

(The following is the rewritten synopsis.)

When the IMC invades Alpha Six, Carol secretly builds up the resistance. But during an operation, a teammate betrays him, leaving him buried deep underground. There, he unexpectedly discovers a research facility left behind by Hammond Industries, along with a strange device. Its software was written by Lin Fan, a transmigrator from a previous generation. After Lin Fan was accidentally killed by a player, he became an AI and began assisting Carol.

This device, the [Dawnstone], can summon people from parallel worlds to help him fight.

With the players joining the battle, the Frontier war takes a decidedly strange turn. The players establish all kinds of bizarre factions across the Frontier, giving the IMC no end of headaches. What the IMC doesn't know is that all these factions answer to an even more powerful force. As the IMC gradually falls into decline, becoming little more than a name and thoroughly infiltrated by players, Carol discovers that the true enemy was never the IMC…