2 players on each side with extra players off of the back of the court (2 teams). A ball is entered over the net. A player returne the ball back over and immediately leaves the court while the next player steps on. There is only 1 contact per side. Players try and find an open part of the court to score. Play to 7.
Add more on court players for a younger team (3 v 3, etc.) Limit the court by making everything behind the 10' line.
Your competitive players make the game more fun.
New hitters rarely miss because of their arm. They miss because of their feet. Build a reliable approach, then time it with your setter.
When your hitter gets stuffed, five teammates standing and watching is how you lose the point. Good attack coverage turns a blocked ball into a second swing.
Coaches spend hours correcting arms in serve receive when the real fault is almost always the feet. Fix the movement and the platform fixes itself.