  Paradigme shift in gauge topology, from instantons to their constituents --
instanton-dyons -- has recently lead to very significant advances. Like
instantons, they have fermionic zero modes, and their collectivization at
sufficiently high density explains the chiral symmetry breaking. Unlike
instantons, these objects have electric and magnetic charges. Their back
reaction on the mean value of the Polyakov line (holonomy) allows to explain
the deconfinement transition. The talk summarizes recent works on the dyon
ensemble, done in the mean field approximation (MFA), and also by direct
numerical statistical simulation. Introduction of non-trivial quark periodicity
conditions leads to drastic changes in both deconfinement and chiral
transitions. In particulaly, in the so called Z(N_c)-QCD model the former gets
much stronger, while the latter does not seem to occur at all.
