AbstractWe prove that the determinacy of Gale-Stewart games whose winning sets are accepted by realtime 1-counter Büchi automata is equivalent to the determinacy of (effective) analytic Gale-Stewart games which is known to be a large cardinal assumption. We show also that the determinacy of Wadge games between two players in charge ofω-languages accepted by 1-counter Büchi automata is equivalent to the (effective) analytic Wadge determinacy. Using some results of set theory we prove that one can effectively construct a 1-counter Büchi automatonand a Büchi automatonsuch that: (1) There exists a model of ZFC in which Player 2 has a winning strategy in the Wadge gameW(L(),L()); (2) There exists a model of ZFC in which the Wadge gameW(L(),L()) is not determined. Moreover these are the only two possibilities, i.e. there are no models of ZFC in which Player 1 has a winning strategy in the Wadge gameW(L(),L()).