Win As Much As You Can:

What makes a good teammate?
In this context, a good teammate is one that you trust; further than that, though, there needs to be mutual trust among all members of the group. That is, every person must trust everyone else, and everyone must trust that everyone else trusts each other and so on ad infinitum. The reason for this is as such: if one person does not believe that you trust another person, they may act assuming that you will act to better your own interests because of a distrust for the tertiary individual. A mutual trust will go a long way in making the team outcome as high as possible, as if every person is undeniably honest, you can assume that every game will result in +1 for every member of the group.

What makes a bad teammate?
A bad teammate is contradictory to the above. They may not necessarily be the one who chooses to hurt the team's interests to better themselves, but if they are untrustworthy, others may try to react to them whether they intend on hurting the team themselves. Another kind of inadequate teammate is the one who takes a slight mistrust of a person and decides that they must compensate for this trust by making the action that they suspect of others.


Possible Improvements:
Make the game sequential: In economics we have learned quite a bit about game theory, and in doing so we have learned that not every game should be simultaneous. By making the game sequential, it is possible to act optimally and lead to an outcome which will be best for everyone.
Add tangible rewards for performing well as a team: The nature of this game makes it so that many people will not consider the gravity of each round, so it would help overall team performance if there were rewards for playing optimally.
Add tangible consequences for performing poorly as a team: As above, it is important that players internalize the mistakes they have made, and by adding some external punishment for betraying teammates, players should consistently play honestly.
Allow players to vote people out of the group after a few rounds: By allowing teams to remove dishonest players from their group, it may be possible to triage the losses incurred by the misfortune of having such an untrustworthy individual on the team.
Remove the equilibrium for individual success: Observant players will notice that it is always equal or better for the individual player to choose the first option, which is the worst for the group. By increasing the group payout to +2 if every person cooperates, this equilibrium will be removed.