The XCOM D&D Project Part 1: Set-Up

This is part 1 in a series. To read part 2, click here.


I love the XCOM series. I’m terrible at it, but I always have a blast whenever I play it. What I’m attempting to do here is to cobble together a set of rules to play an XCOM-inspired game using D&D 5th Edition mechanics. Aliens aren’t really a thing in D&D, but there are plenty of invasive, extraplanar beings that can serve as substitutes in a pinch. For this example, I’m using demons and devils, but practically any kind of enemy could be used instead.


So the premise for this game is that demons and devils have been making incursions into a fantastical world, and the kingdoms of the world have put together an organization with the sole purpose of stopping the fiendish invasion. The organization will be understaffed and underfunded, and facing increasingly more deadly foes, but with proper management and tactical thinking the fiends can be defeated.


For this game to work, the players need to feel like they are in control of the organization, but at the same time feel like the world is out of control. They will have to make hard choices, and if they don’t execute their plans perfectly, then sacrifices will have to be made. The enemies must outnumber the players, but are generally individually weaker. Like the XCOM series, the enemies cannot be defeated by sheer force, there will always be more. Instead, the players must uncover their weakness, find their fortress, and ultimately defeat their leader. Otherwise the war will drag on indefinitely until the players are overwhelmed. Both players characters and enemies will have generally lower hit points than they would in base 5th Edition, to encourage a brisk and deadly game. Research is a key part of the XCOM series, and I expect it to be important here too. Taking corpses to be studied, and capturing live enemies will allow them to be studied by the research team and provide insight on the enemies and more advanced technology for the players. Research should always provide some benefit to the players, even if it is a very small one. This game will require a lot of bookkeeping, so keep that in mind when you go into this. Is this a bad idea for a tabletop game? Maybe, but I’ll have fun making it nonetheless.


While I’m too early in the design of this game to nail down any of the game’s mechanics, coming up with a basic structure for how the game is played is a great place to start. If you haven’t played an XCOM game, I’d recommend playing one of them so you can understand what I’m trying to replicate. The game will start with the party choosing a location for their base, then creating three characters per player. The characters are essentially zero-level characters (perhaps I will rework how character creation works to make the game work more like XCOM) that gain a class after their first “rank up.” After character creation, the introductory mission begins, where each player picks one of their characters and sends them out on the mission. Fortunately, like D&D, XCOM is a turn-based game, so very little has to be restructured as far as individual missions go. Instead of initiative rolls, the party will take a turn as a group then the enemies will take a turn as a group. Missions have objectives, which include “eliminate all the enemies,” “rescue X number of civilians,” “steal intel from the enemy,” “rescue an enemy captive,” and more. Missions end when the objective has been completed or when the entire party is dead or evacuated. Characters only gain experience at the end of missions, calculated from the number of enemies they killed (for a more authentic experience only count enemies they dealt the killing blow to) and how difficult the mission was. After the mission, wounded soldiers are sent to the infirmary for set amount of time based on how wounded they are. If enemy corpses were recovered or enemies were captured alive, the party can choose to research one of them. Research takes time, and traveling to and from missions also takes time. The players can choose when to progress time, but they must keep in mind that the fiends are also doing things in the background as time passes. Base management will be a big part of this, as well as monitoring the world for fiendish threats. When a threat is spotted, the party can send another group of characters. My instinct is to say that each mission consists of one character per player, so the number of players determines the size of the operation. Maybe support units (a tamed monster? a mercenary?) can be added that can be controlled by the players or the GM. Players go on missions, they complete the missions, they return, they research, they expand, they examine, they repeat. At certain points the GM will introduce story missions that will allow the players to get closer to discovering how to defeat the fiend threat as well as introduce new enemies, technology, or mechanics. Ultimately the players will discover the fiend fortress and have to fight their way through it to put an end to the invasion. This fight will put everything they’ve learned to the test.

What’s Next

Now that I have this set-up out of the way, I can start looking into the specifics of how to make this game work. In Part 2 of this blog series, I’m going to look into how D&D and other systems handle running an organization, and what does and doesn’t work for what I’m trying to do here.

Leave a Reply

Your email address will not be published. Required fields are marked *