Primus is deducted from the game Neutron from Robert A. Kraus (I). But while Neutron is for 2 players and heavily unbalanced, Primus is for 2-4 players and by using 4 instead of only 1 neutron it is a really great enhancement to Neutron.
The whole board is 8x8 spaces, but the outer rows and columns serve as home bases for the players only. The game itself is played on the 6x6 inner part of the board.
The 4 neutrons are placed in the middle of the board. Object of the game is to get the most points by moving these neutrons to the home bases. The neutrons are worth 3, 6, 8 and 10 points, depending on the order, when they have been captured. That means, the first captured neutron gives 3 points, the second 6 and so on.
After all, Primus is much better balanced than Neutron and the clever point values forces the players to think at more than just at capturing every reachable neutron.