My idea is to have a random chance of entering a mission every time you use a train.
The load screen would look normal, but when you get there you have been dumped into a mission.
Some suggested missions:
-Your train is being held up.
-The train has crashed and you are in between zones, just outside the train is the ruins of an old theme park.
-The train has been transported to another dimension and is floating above a floating island full of beasties.
-The train is embedded in the sand beach, somehow transported back in time and is now being attacked by Romans.
The active mission is temporarily overwritten while in this mission. When on a team, each member has a chance of getting the random mission, but the team will not get two at the same time. Once one member gets a random mission the rest are ineligible. If one of the team members is already in an instanced mission then none of the rest of the team are eligible to get a random train mission.
Once the first member of a team gets a random train mission a pop-up alerts the rest of the team that the member needs help and they can all jump on any train to join them.
New badges can be implemented for these missions. New "Cowboy" themed villains can be created using the dual pistols power and used exclusively in these missions.
That's the basics of my idea. What do you think?
~tink