https://3drealms.com/catalog/ion-maiden_56/3D Realms' Website wrote:3D Realms (Duke Nukem 3D, ROTT, Prey, Max Payne) is excited to bring back our famous Build engine, which powered Duke Nukem 3D, Blood, Shadow Warrior and other 90's hits. Of old-school throwback games, ION MAIDEN is the real deal, using our original tech from that famous era that launched the FPS genre. Welcome to ION MAIDEN! Shelly “Bombshell” Harrison earned her codename as a bomb disposal expert for the Global Defense Force. When transhumanist cult mastermind Dr. Jadus Heskel unleashes a cybernetic army on Neo DC, Shelly decides it’s time to start chucking bombs rather than defusing them. Her journey will leave trails of blood and gore in huge, multi-path levels filled with those famous colorful keycards and plenty of secrets and Easter Eggs to discover behind every corner.
It claims to be Early Access, but it is really just rebadged Shareware. Seems legit.