Using an approach from finite group representation theory we construct quaternary non-projective codes with parameters [ 6 9 3 , 6 , 4 8 0 ] 4 , [ 1 3 8 6 , 6 , 1 0 0 8 ] 4 , [ 2 0 1 6 , 6 , 1 4 8 8 ] 4 , quaternary projective codes with parameters [ 2 3 1 , 6 , 1 6 0 ] 4 , [ 4 6 2 , 6 , 3 3 6 ] 4 and [ 6 7 2 , 6 , 4 9 6 ] 4 and binary projective codes with parameters [ 6 9 3 , 1 2 , 3 2 0 ] 2 , [ 1 3 8 6 , 1 2 , 6 7 2 ] 2 , [ 2 0 1 6 , 1 2 , 9 9 2 ] 2 as examples of two-weight codes on which a finite almost quasisimple group of sporadic type acts transitively as permutation groups of automorphisms. In particular, we show that these codes are invariant under the 3 -fold covers 3 ̂ M 2 2 and 3 ̂ M 2 2 : 2 , respectively, of the Mathieu groups M 2 2 and M 2 2 : 2. Employing a known construction of strongly regular graphs from projective two-weight codes we obtain from the binary projective (respectively, quaternary projective) two-weight codes with parameters those given above, the strongly regular graphs with parameters (4 0 9 6 , 6 9 3 , 1 5 2 , 1 1 0) , (4 0 9 6 , 1 3 8 6 , 4 8 2 , 4 6 2) , and (4 0 9 6 , 2 0 1 6 , 9 9 2 , 9 9 2) , respectively. The latter graph can be viewed as a 2 - (4 0 9 6 , 2 0 1 6 , 9 9 2) -symmetric design with the symmetric difference property whose residual and derived designs with respect to a block give rise to binary self-complementary codes meeting the Grey–Rankin bound with equality. [ABSTRACT FROM AUTHOR]