Time Crystal 2 - Delsaron's World (The Eridon Chronicles)

On their return trip to Eridon, Heathcliff and his five half-caste friends fall through a mysterious wormhole and land on an alternate Earth where the Nazis achieved world domination.

Separated by misfortune, Heath and Con are sent to a forced-labour camp while Kirsty and Katarine end up specimens in a genetic laboratory. Only Aidan and Charlotte manage to flee into a grim fascist world, where they encounter Omega-class outcasts condemned tp death by their own impure genes.

While helping the rebels plan a glorious revolution, Aidan and Charlotte are reunited with Heath, Con and an American Airman named John Land. With their superior psionic powers, Heath and his friends assume it will be easy to help the Omega rebels overthrow their evil oppressors.

But the mysterious Great Leader has dark powers of his own, numerous machines to aid him, and his own army of genetically modified clones at his beck and call. He even has a trans-dimensional gate-machine which he uses to pirate alien technology from other dimensions€¦

Also part of the Eridon Chronicles:
Half-caste
Time Crystal 1 - the Convergence
Time Crystal 3 - the Icosahedron
Time Crystal 4 - the Singularity
Rise of the Unmaker Past - Dawn of the Nightbringer
Rise of the Unmaker Present - Zenith of the Daystone
Rise of the Unmaker Future - Dusk of Uncreation
The Mind Eaters Book 1 - The Dodecahedron
The Mind Eaters Book 2 - The Chronopsyker
The Mind Eaters Book 3 - The Old Ones