Although CD Projekt Red is far from perfect, GOG's version https://www.gog.com/game/xcom_terror_from_the_deep https://www.gog.com/game/xcom_terror_from_the_deep

Although CD Projekt Red is far from perfect, GOG's version https://www.gog.com/game/xcom_terror_from_the_deep https://www.gog.com/game/xcom_terror_from_the_deep is DRM free and includes the manual. Unsure if the old copy protection has been patched out. Looks like there's also an engine reimplementation: https://openxcom.org/ https://openxcom.org/