He is just chilling

I would like to know as well

Probably he might show up again if there's a sequel for this in the future. Usually a character that's suddenly missing usually shows up again on the certain next episode or season of a series, so probably Mike would do that too.

Mike decided to stay behind in the saferoom, where it's safe and warm. However, in a future update it may be possible to change his mind. Plus, since the campaign's files are all basically open source, anyone can implement Mike into their own project.

That would be really cool, when i first played it with friends we all thought that Mike would stay with us until the end of the Campaign as long as we kept him alive, it was kinda sad when he stayed in the saferoom

Man, I hope mike's alive in the next chapters. I don't want him die tho.

You better not play the map on Versus then xD

Left 4 Dead 3 takes place where Mike is the Sole Protagonist Solo Surviving Everything.

i may have found a way to keep him, i have finished the map with him following me and my team ;)
my man just need something to clench his thirst

how do you add Mike Into L4D campaigns?

There's a cola in Chapter 3 that you need bring to the saferoom! As soon as Chapter 4 starts Mike will still be in your team