The scramble volleyball game or drill is one which is quite useful for working on out-of-system play and getting players committed to keeping the ball in play
You can use the virus volleyball game to work out-of-system play on one hand and on recognition of it and proper defensive positioning for it on the other.
Here's an alternative way you can focus on volleyball serve receive within the context for more normal game play using bonus points.
This volleyball game variation allows you to focus your players on key developmental or coaching points while working within on overall game play structure.
By narrowing the area of play, this volleyball game puts a premium on control and problem-solving with lots of potential for focused work and player evaluation.
This is a volleyball game which can be useful to assess the competitiveness of players and their relative game play effectiveness, potentially in a try-out.
Here's a game I saw at UCLA which works on hitters challenging the block, with additional serve receive and free ball attacking
This is a fairly simple wash-scoring based game which gives players an opportunity to work on both serve receive offense and transition attack to score points.