Is this something you should try to do with an RTS engine? I don’t know, but HELLKNIGHT61 has accomplished the dream-who am I to deny it? You can find Age of Doom on ModDB. The whole thing reminds me of the days of Warcraft custom games, to be honest. It has its own tutorial and a four chapter campaign, with a fifth chapter yet to be released. So Doomguy walks around and uses a super shotgun, sure, but there are also cyberdemons and pinkies and everything else you’d expect to see. Most notably, it ports sprites, projectiles, and effects from the original Doom into the Age of Empires 2 engine. Age of Empires II released originally in 1999, however with the 2013 release of Age of Empires II HD the modding scene on the workshop page for the game has exploded in recent years as Age of Empires II to this day is still one of the most popular strategy games of all time. The Age of Doom mod for Age of Empires 2 is a campaign that ports ideas, themes, and bits of story from both Doom and Doom 3, sampling audio and enemies from both. “I wanted to resurrect the original DOOM for Age of Empires 2 game engine,” HELLKNIGHT61 says in describing the mod. Modder HELLKNIGHT61 was aware of both of these things, and they have used the Age of Empires 2 engine to make Doom into a third person, isometric RTS… shooter… thing. Doom is also a top tier, all-time success. Age of Empires 2 is a top tier, all-time success of gaming.

Mods for age of empires 2