This one is quite a hit in TF2. I got the idea of bringing it to blockland from the duck playertype.
Basically you have 2 teams, one is made up entirely of pyros, and the other; scouts.
The scouts are not seen as scouts until they die, and they cannot use weapons or anything like that unless they are the last prop standing
Pyros can spam the flame and shotgun all they want, however, with each bit of possible damage dealt (as in they shoot the shotgun and either miss or hit) they lose health, so they're not so tempted to spam flames at everything they see.
Luckily for everyone, there is a CP at the center of every map. When they walk over the CP, it restores their health. But they can only get this refreshment once, they they have to wait until it refreshes before they can use it again. The CP is on a universal timer (it doesn't have a refresh time for each individual player) and refreshes every minute or minute and a half.
For the first 30 seconds of the round, Props hide and Pyros don't move, however, during the setup time, pyros can shoot.
When a prop is not the last prop standing, they left click to engage prop lock, this enables them to look around without turning their prop as well so they don't expose themselves while checking their 6
Some Ideas for Props:
-Duck
-Fire Hydrant
-Trash Can
-Street Sign
-Basically anything relatively small that can be made of default bricks and colors.
Edit:A few examples: