Quintus

Quintus, or Quintun, is a 2003 game by Martin Windischer.

The game is played on a 10*10 hexagonal board. 

There are enough white and black pieces, and enough neutral stones of five different colors.

Definitions:

• the 54 hexes on the edges are the ring
• the remaining hexes are the playing area

Rules:

• On her turn, the player either:
• drops a friendly piece on an empty hex inside the playing area
• drops, on the ring, one neutral piece of a new color
  
• this piece must be at least five empty hexes from other neutral stones in both directions of the ring
• drops, on the ring, two neutral pieces of a color already played
• these pieces must be adjacent to pieces of the same color
• Wins the player that either:
• connects a friendly group with four different neutral colors
• connects two friendly groups, each with three different neutral colors

In the next diagram (from a real match), White resigns: there's no possibility for his large group to connect to a third neutral color

  

This is imho a very good game, a connection game that does not have a fixed connection goal. The only point where this could be improved is in the condition of dropping the first neutral stone of a new color (so to remove the arbitrary distance of five empty hexes). The suggested new rule: 

• drops, on the ring, one neutral piece of a new color in a side with no neutral pieces already in it (including corners) if this is possible, otherwise any ring hex

There are six edges for five colors. If a small number of neutral colors get to have large groups, a new tactical avenue would open by dropping the new neutral color anywhere in the ring.