<!-- Yandex Games SDK -->
<script src="https://yandex.ru/games/sdk/v2"></script>
<script>
    YaGames
        .init({
            adv: {
                onAdvClose: wasShown => {
                      console.info('adv closed!');
                }
            }
        })
        .then(ysdk => {
            ysdk.adv.showFullscreenAdv({
          callbacks: {
          onClose: function(wasShown) {
            // some action after close
        },
          onError: function(error) {
            // some action on error
        }
    }
})
        });
</script>

Итоговая интеграция Я.игр

<!-- Yandex Games SDK -->
<script src="https://yandex.ru/games/sdk/v2"></script>
<script>
    YaGames
        .init({
            adv: {
                onAdvClose: wasShown => {
                      console.info('adv closed!');
			

                }
            }
        })
	.then(ysdk => {
            ysdk.adv.showFullscreenAdv({
          callbacks: {
          onClose: function(wasShown) {
            ysdk.features.LoadingAPI.ready();
	  },
          onError: function(error) {
            ysdk.features.LoadingAPI.ready();
          }
    	}
	})
	window.ysdk = ysdk;
});
var yalangvar = ysdk.environment.browser.lang;
</script>