Advances in generative AI (GenAI) have enabled the development of AI-based non-player characters (NPCs) to engage in natural language interactions with players via chat or speech. Commonly, video games use predefined dialogue options to communicate with NPCs. However, little is known about how GenAI-based communication affects players’ perceptions of NPCs. We developed a speech-based video game where players interact with three NPCs using different communication modalities: pre-scripted dialogue options, a GenAI-based chat, and GenAI-based speech interaction. We conducted a user study ( \(n~=~25\) ) to examine how different communication approaches impact player’s perceptions of the NPCs, specifically their empathy towards the NPCs. Results show that players expressed significantly higher empathy toward NPCs they could interact with freely via speech or chat, with speech surpassing chat in fostering empathy. We further discuss the potential and limitations of GenAI-based NPC communication and offer insights for game designers on creating more engaging and believable NPCs.