This study examines the influence of perceived AI features on user motivation in virtual interactions. AI avatars, being disclosed as being an AI, or embodying specific genders, could be used in user-AI interactions. Leveraging insights from AI and avatar research, we explore how AI disclosure and gender affect user motivation. We conducted a game-based experiment involving over 72,500 participants who solved search problems alone or with an AI companion. Different groups experienced varying AI appearances and disclosures. We measured play intensity. Results revealed that the presence of another avatar led to less intense play compared to solo play. Disclosure of the avatar as AI heightened effort intensity compared to non-disclosed AI companions. Additionally, a masculine AI appearance reduced effort intensity.