Koban Series Stephen W Bennett (Books 1-3)

Koban: We colonized seven hundred planets. Humankind enjoyed the benefits of expansion room and the end of wars. We even disbanded our military.
Then the Krall found us.
The Krall have used thousands of years of combat to select the genes of the strongest and fastest warriors. They are a species determined to dominate the entire galaxy, through destruction and annihilation of every opponent.
Koban is an uninhabited high gravity planet with impossibly fast savage animals, which employ organic superconducting nerves. This deadly world is where the Krall tested humans for war capability. We are useful only if we can fight well. If not, they will destroy us swiftly, as they have others. They already have slave races, and we are poor tasting meat animals. The Krall will use us, if worthy, to seek physical perfection using the attrition of war, one planet at a time.
Growing weary of human physical weakness, the ruthless Krall are on the verge of a decision to eliminate our race quickly. A ship containing bio-scientists is captured for combat testing on Koban. The urgent choice for Captain Mirikami and the scientists is simple: Prove we can produce better, smarter fighters, or humanity is doomed to rapid extermination, rather than the slow eradication the Krall prefer.
However, the Krall are only part of the problem. We have to survive Koban’s gravity and superfast animals. The huge tiger-like rippers with skin contact telepathy are predators too fast even for armed Krall to face. The Human genetic solution: If you can't beat them as you are, become like a ripper.
The Krall will learn another species can bypass natural selection.



Koban: The Mark of Koban: Already faster and more powerful than the last 17 species that they have eliminated or subjugated, the Krall have set their sights on humankind.
After testing humans on their future home world of Koban and finding them worthy opponents, the Krall start a war of slow extermination with the rest of humanity. This war is intended to last generations as they apply their own version of “natural selection” to cull their weaker warriors in combat, purifying the Krall gene pool with finest warriors for breeding.
Why? The Krall desire to become powerful enough to eventually live on the world of Koban, where the impossibly fast and powerful animals have proven to be too much for the Krall to master without technology to help. The only way the Krall survive on Koban is to live in isolated and well-protected domes, safe from the fauna they fiercely desire to dominate. Only through the attrition of war will the Krall perfect their bloodline to become the masters of Koban.
Before the Krall departed Koban to start their new war, they destroyed the protections that allowed the Krall to survive on this dangerous planet. The Krall left the humans on the planet to fall victim to the high gravity, to the fast and savage wildlife and its deadly predators. Big mistake. They should have killed the test "animals" themselves! The bio-scientist they left behind add Koban genes to the next generation of humans. They are becoming what the Krall sought to be.
The humans on Koban, locked in a struggle for their own survival, return to the stars to help humanity fight and, outnumbered, take the war to the Krall.



Koban: Rise of the Kobani : he Kobani use captured Krall ships to return to Human Space. They seek expert training for their genetically modified fighters, modern weapons and new medical technology. There’s a possible block to this help, in the form of death penalty laws of the Planetary Union, prohibiting gene modifications of humans. A holdover from the Gene War, which nearly extinguished humanity.
A perilous descent through a war torn planet’s space defenses is a first step. A Krall ship and its heavily armed crew have to be destroyed on the ground, while a watching hostile Special Ops force decides if the Kobani should be trusted or killed. Fighting their way between a rock and a hard place, they prove they are a match for the Krall.
Exploration at home reveals startling alien neighbors, and a habitable world next door. A remarkable genetic discovery there will forever alter the Kobani. Wining allies, Captain Mirikami forges a bold and dangerous plan, to strike deep into the heart of Krall territory. A place the enemy is confident that puny “animals” can’t reach, let alone attack.
Simultaneous Kobani raids damage Krall war manufacturing, buying time for humanity. However, the Krall have a deadly ancient weapon that none expected. Retaliatory escalation of the war has been triggered, and if it doesn’t go as the Krall plan, entire planets and their populations could be shattered.