Members of the community, I'm sorry to report that certain sandbox-type games have been declared dangerous and unsafe to play. Here are a few warnings for your safety:

Dwarf Fortress: While most individuals were found to quit the game early due to its complex nature, some individuals were able to continue playing for extended periods of time. Symptoms of prolonged use include confusion, distress, and a tendency to call unfortunate things "Fun."

Ace of Spades: This game has been found to be midly addictive, although it's proven so dangerous that it can kill off affected individuals before the addiction can develop fully. This is mostly due to excessive amounts of griefing, trolling, and hacking, although hacking has lately been replaced with an less serious trend of serverside hit verification. Experts predict that improved admin controls could cause this game to become pandemic.

Minecraft: This game was found particularly addictive to nearly all individuals. Exposure for as little as an hour caused most individuals to become addicted. Addictions were found to develop rapidly and cause such symptoms as a strong desire to display buildings, particuarly in the form of "Let's Play" videos and similar media. Fortunately, the cost of a Minecraft addiction has caused some individuals to resist exposure.

(I love off-topic now. I also love WAY too many sandbox or sandbox-ish games. For those of you wondering, this random post was the result of me developing a sudden and serious Dwarf Fortress addiction).

I suggest a sandbox mode where damage and weapons are removed, and you could join a certain amount of teams...

Blue: You can place/remove all other blue players' blocks.
Green: You can place/remove all other green players' blocks.
Independent: Only you can place and remove your own blocks.

Not saying an infinite block count.