From the Z-Man Games Website
Neuroshima Hex 3.0 – 3 Player Game
Neuroshima Hex 3.0 introduces a new way to play the game: the
3-player game. There are many different ways to go about starting a
3-player game. Today, we explore all the way that you can play
Neuroshima Hex 3.0 is you just so happen to be 3 people sitting at the
table.
OPTION #1: DEATHMATCH
While its name may suggest a grand battle that will surely not end
well for two people involved, this 3-player option is more about
negotiations than tactics.
If a player loses his HQ during the game, his tile is removed from
the board, as well as all his Units. This player is now out of the game
and two players remain.
OPTION #2: DEATHMATCH WITH AN OPTIONAL SCORE RULE
This option is a twist on the first option where the aim is not to
eliminate your opponents, but to attack them as much as possible, in
order to reach a set amount of points.
At the beginning of the game, players set their HQ damage counters to
0. In this option, HQs have unlimited hit points, and every time a
player’s unit hits an opponent’s HQ, the wounds inflicted count as
points that are marked on the attacking player’s counter. The first
player to make it to 20 points is declared the winner. If no one has
made it to 20 points before the end of the Final Battle, the player with
the most points is declared victorious.
OPTION #3: 1 PLAYER VS A TEAM
As its name states, this option will put two players against one
(called the Loner). Will the Loner be able to outsmart the team?
The Loner sets his HQ damage counter to 20 and the team members each
set theirs to 16. The first to destroy an opponent’s HQ wins the game.
If two opposing HQs are destroyed in the same battle, the team wins. If
no HQs are destroyed before the end of the game, the person with the
most damage points left on his HQ marker wins.

There you have it! You will soon be able to play Neuroshima Hex 3.0 with only 3 players!