The phrase "be game" typically means to be willing to do something, especially something adventurous or challenging. Some synonyms for this phrase include to be ready, to be prepared, to be up for it, to be eager, to be enthusiastic, to be keen, to be willing, to be open-minded, to be daring, and to be fearless. Depending on the context, different synonyms may be more appropriate than others. For example, if someone is hesitant to try a new activity, you might encourage them by saying "be game!" or "be up for it!" whereas if you are discussing a daring adventure, you might say "be fearless!" or "be daring!