I solved the game in less than two minutes: the game's solution requires that either player leaves 5-groups with one additional remaining unit per turn starting from two units; ie: winner leaves two units from first 5-group, then leaves three units from second 5-group, finally leaves five units from last 5-group. Since rules define a take as variable min-1 max-3 units, player taking first from last 5-group necessarily loses; ie: 1st takes 3, 2nd(winner) takes 1; 1st takes 1, 2nd takes 3; etc.