Yes, this image is about the "holdout" mutation system.
You can play it by going on "Mutation" in the main menu, and select "change mutation", then select "
holdout".
There is also a "
dash" and "
shootzones" mutations that are part of the EMS.
After selecting the mutation, start a new game through menu.
Or if you want test directly, type e.g.
map c1m2_streets holdout
In console.
There is only a few maps with holdout mutation and you can also download some more on steamworkshop
Here is some:
https://steamcommunity.com/sharedfil.../?id=371215032
In my opinion is a great mutation.
If you like it, you should try some "
Let's Build Maps" that was a similar approach.
https://www.gamemaps.com/l4d2/lets-build/
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