I really like 'XCOM in the Star Wars Galaxy'. It's a fun crossover where the XCOM troops are dropped into the Star Wars universe. They use their high - tech weaponry and tactics against the Sith and the Empire. It has some great battle scenes where XCOM's stealth technology clashes with the Force - using Sith Lords. Also, 'XCOM and Halo: The United Front' is quite good. The XCOM soldiers and the Spartans join forces to combat an alien invasion that is more powerful than either has faced before.
One idea could be a crossover with the Mass Effect universe. The Xcom soldiers could encounter some of the alien races from Mass Effect and have to work together or face off against them. Maybe the Xcom team has to deal with the Reapers in some way.
One popular xcom crossover fanfiction is the one where XCOM agents cross over with the Mass Effect universe. It's really interesting to see how the XCOM combat strategies are applied in the fight against the Reapers. Another great one is the crossover with the Warhammer 40K universe. The grimdark setting of 40K and the high - tech nature of XCOM create a really unique blend.
You could also focus on the technology aspect. Templars are used to a certain level of technology in their world. How do they react to Xcom's advanced weaponry and high - tech facilities? Do they see it as a means to enhance their own abilities, or are they skeptical? This exploration of the relationship between different technological levels can add depth to the fanfiction.
You could also try Wattpad. Although it's more known for general fiction, there are some XCOM crossover fanfictions there. Look for tags like 'XCOM', 'crossover', and related sci - fi franchises. Sometimes, authors will post their work on multiple platforms, so checking different ones gives you a better chance of finding really good XCOM crossover fanfiction.
First, you need to be really familiar with both the Xcom 2 world and the world you want to crossover with. Know the characters, the settings, the rules. For example, if it's a crossover with Warhammer 40K, understand the grimdark nature of that universe and how Xcom's more tactical and strategic elements can fit in.
First, do some research on both the Xcom universe and the templar lore. Know their strengths, weaknesses, cultures, etc. Then, come up with a basic plot idea. For example, a group of templars could be accidentally transported to the Xcom world. After that, create your main characters from both sides and start thinking about how they'll interact.
Shepard from Mass Effect could be a main character. They could lead the XCOM forces in a joint mission against a common enemy. Their leadership skills would be very useful in coordinating the two very different groups.
Another aspect could be the exploration of the political and cultural differences between the two universes. XCOM is mainly focused on Earth defense, while Mass Effect has a complex galactic political system. A fanfiction could explore how the two groups interact when it comes to things like trade, alliances, and dealing with common threats. For instance, how would the XCOM Council (if there was one in the crossover) deal with the Citadel Council's decisions and vice versa?
Well, in 'xcom mass effect crossover fanfic', perhaps a cool concept is the interaction of the characters. Imagine Commander Shepard teaming up with XCOM operatives. They could share their combat strategies and knowledge. Also, the idea of using Mass Effect's biotics in XCOM missions or having XCOM's psi - ops in the Mass Effect universe could add a whole new layer of excitement to the story.