Another aspect could be a story where the two universes are merging due to some sort of interdimensional rift. The Overwatch characters and the Titanfall 2 pilots have to team up to close this rift. During this process, they learn about each other's worlds, cultures, and fighting styles. There could be some really cool interactions between the more tech - savvy Titanfall 2 characters and the diverse heroes of Overwatch.
A crossover could involve the characters swapping abilities. Imagine Tracer from Overwatch having the ability to call in a Titan like in Titanfall 2. Or a Titanfall 2 pilot having the ability to use some of the support abilities of the Overwatch heroes, like Mercy's healing. This would create really interesting and unique combinations in combat scenarios.
The plot could center around a new threat that only the combined forces of Titanfall 2 and Overwatch can defeat. For instance, a powerful alien race that has the ability to disrupt technology, which affects both the high - tech Titans and the various advanced weapons and gadgets in the Overwatch universe. So, heroes from both sides must put aside their differences and fight together.
A really interesting storyline could be centered around the conflict between the two factions in Titanfall and how the Overwatch heroes get involved. Maybe the Omnics from Overwatch are somehow related to the IMC or the Militia in Titanfall. This would lead to a complex web of relationships and battles. The Overwatch heroes would have to adapt to the Titanfall combat style, and the Titan pilots would learn to work with these new, diverse heroes.
Pharah and a Titanfall scientist. Pharah is a highly trained soldier with a focus on aerial combat. A Titanfall scientist might be researching new ways to improve Titan mobility or weaponry. Their alliance could be born out of a need to create some new kind of weapon or technology. The scientist could use Pharah's combat knowledge to better understand how their creations will be used in actual battles, and Pharah could get access to some really advanced tech.
One idea could be an Overwatch crossover with the Star Wars universe. Imagine Tracer using her time - traveling abilities in the middle of a lightsaber duel. Another could be a crossover with the Harry Potter world, like Pharah flying on her rocket launcher over Hogwarts. And a crossover with the Marvel universe, where Reinhardt teams up with Thor to fight some powerful villains.
One idea could be a crossover with a mecha anime. Picture the Titans from Titanfall engaging in battles alongside the giant robots from an anime like Gundam. The different piloting styles and technologies could create some really cool action scenes.
Another interesting concept is that some of the Titans could be modeled after the RWBY characters' weapons or fighting styles. For instance, a Titan with a scythe - like weapon similar to Ruby's Crescent Rose, and it could have a special ability based on her speed and agility.
A crossover with a cyberpunk - themed story could be really cool. Genji's cybernetic enhancements would fit right in. He could be on a mission in a dystopian city, facing off against powerful corporations and their enforcers. Along the way, he might meet new allies who are also fighting for justice in this harsh environment.
Another concept could be a story where a character from Halo, say Master Chief, gets transported to the Overwatch universe. He has to adapt to the different rules and powers there while trying to find a way back home. Along the way, he could form unexpected alliances with Overwatch heroes and learn about their world, and they could learn from his military discipline and combat experience.
Another interesting concept could be a crossover in which the technology from TF2 is integrated into the Overwatch universe, or vice versa. For example, the Medic's healing technology being used to enhance the Overwatch medics' abilities. This could lead to some really cool character interactions and story developments as they learn to work with new equipment and each other.
A great concept could be a crossover tournament. The two teams, TF2 and Overwatch, compete in a series of challenges. These challenges could include things like a sniper - only round where Widowmaker from Overwatch and Sniper from TF2 go head - to - head. Or a melee combat round with Reinhardt and the Demoman. It would be a chance to explore the different abilities and personalities of the characters in a competitive setting.