Crimson Worlds

They hang you or they hand you a rifle. In the crowded, rotting 23rd century of Crimson Worlds, Earth belongs to the Superpowers, and the condemned belong to the Corps. Take the black uniform, ship out to some contested rock a dozen light-years from home, and die for a flag that would just as soon have shot you. This is powered-armor military science fiction with the boot still in the mud: colonial Marines fighting the great powers' proxy wars across the frontier, told from inside the helmet. At its center is Jay Allan's flagship sequence, the nine-book arc of Erik Cain — a slum kid marked for execution who becomes the age's hardest soldier — running from Marines through The Cost of Command, A Little Rebellion, and on to the war against the First Imperium, an ancient machine intelligence that turns human quarrels into a fight for survival. Around that spine cluster the continuations: Crimson Worlds Refugees, Successors, and a run of Prequels, plus Kindle Worlds offshoots by other hands (Edward M. Grant's Legionnaire among them) — one universe, many campaigns, honestly uneven. What marks it is the soldier's-eye austerity: loyalty, attrition, and the slow corruption of the men who send others to bleed. Newcomers start at the top of the line — Marines, book one of the Cain saga — and follow it in order. Everything else is reinforcements.