GRO is an abstract strategy game for 2 players.  Each player controls the growth and expansion of a strain of bacterium within the confines of a Petri dish.  The goal is to become the dominant strain.

Each player starts with a single germ.  Germs may grow and divide to produce more germs, which may grow and divide to produce more germs, which may grow and get the idea.  Germs may also move, and they may attempt to surround opposing germs.  When a germ is surrounded, it dies.

The Petri dish contains 4 goal areas.  The first player to gain exclusive control of 3 of the 4 areas, wins.


  • Construction: 1-2 hours
  • Number of Players: 2
  • Complexity: Medium
  • Playing Time: 1-2 hours
  • Age Group: 13+
  • Skill vs. Luck: 100% skill
  • Parts Needed: Everything you need is in the file.



GRO is available in Portable Document Format (PDF.)  The file size is 2.5MB.

Pages Content
1 Cover Art by Randy Farran
2 - 5 Rules
6 - 7 Help Sheet - print 1 for each player
8 Petri Dish
9 Germ Markers



If you would like a hard copy of GRO, you may be able to find one gathering dust at your local game store.  Or you can buy it from one of these online retailers:

Kampf der Kulturen


A German language version GRO is available from Sphinx Spieleverlag  It was translated by Henning Poehl and re-titled Kampf der Kulturen. The German version features colorful artwork and fuzzy germs.

Zillions of Games


You can play GRO on your PC thanks to Stephen Tavener and Zillions of GamesZillions is a versatile engine that can be programmed to play just about any 2 player, abstract game.  Stephen wrote a Zillions game file for GRO.  Thanks Stephen!


The Greenwood Gamers
"If you enjoy a hard fought game of chess, you will probably like GRO."
JJ Armour, Mensa Mind Games 2000 participant
"A strategy game that I wouldn't want to play again, but I'd certainly consider purchasing it for some people I know."
Ken Kaufman, Mensa Mind Games 2000 participant
"I really thought the germ analogy worked well."
Matt Ryan of Envelope Games
"A darn fine game."
Pierre-Nicolas Lapointe on JesWeb
"Un jeu à découvrir pour les amateurs de stratégie abstraite et originale."
Tom Vasel
"If you like Go, give this much simpler game a try, I think you'll be pleased."
Board Game Geek
Visit the GRO page on the geek.
Noble Knight Games Logo
Adobe Acrobat
Hard Hat
German Flag

Updated: 2015-AUG-30

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