3drealms (Apogee) still sells the registered version of this game & you can buy it on Steam or GOG. https://3drealms.com/catalog/realms-chaos_9/ Steam https://store.steampowered.com/app/358320/Realms_of_Chaos/ GOG https://www.gog.com/game/realms_of_chaos?pp=215bb47da8fac3342b858ac3db09b033c6c46e0b

The shareware version includes the first episode and its very easy to find online.