We already have fighting areas (PVP) in our events world, here you can fight people to the death, but sadly because of abuse all items are kept on normal deaths within that area.
We also have an arena which is used for specific events throughout the year, this includes PVP. As for Hunger Games we did this too as a special event earlier this year; our current PVP areas are really "hunger" games styled anyway, you can just set yourself and fellow players specific rules on not to leave/only use certain items if you wanted?
As for spleef this too is coming out later this summer, we do hold the occasional spleef event as a server too. You can feel free to make your own spleef arena to play on if you wanted to though, it is quite easy to do so with some snow blocks and a few shovels.