To solve this problem the Soosõrv-N advancement was proposed and certified by RIF.
When the white player puts the 4th move and declares the number of fifth moves, the number has to be not less than 1 and not greater than N, instead of the default value 4 for N in the original Soosõrv opening rule.
[2] Depending on the value of N this rule gives an average to big variety of new playable variants in a growing number of openings.
Soosõrv-5 is very close to Taraguchi concerning a number of playable positions.
Soosõrv opening rule was an official opening rule for European Renju Championship in 2008 and a couple of minor international tournaments.