Anticipation is an amazing tool that drives curiosity and a sense of excitement to anyone that experiences it. you can use that same feeling to promote your game. For most game developers their process of promoting their game comes after the completion of the game. Developers may release game play and teaser trailers after production, however for most indie developers that have little social media presence this is way too late.
Social media is a great tool to build up anticipation. Instead of releasing promotional content after your game is completed, document your progress on social media as you create it. These videos do not have to be long vlog style videos (although they can be and for platforms like YouTube vlogs are ideal) they can be short 30 second videos that show screenshots with a quick voice over. A good reference to these types of videos are the "My Daily Routine" TikTok videos, these style of videos do well with the algorithm as well.
By documenting your progress as you create your game you give people a reason to tune in every week to see your progress. This also makes them feel like they are apart of the process and it makes people become emotionally invested. Naturally, after you complete your game and release it to the public your viewers will be more inclined to play it as they have a sense of investment into your game. This strategy also has the added benefit of increasing your social media following. So next time when you release another game you have more of an existing audience to advertise to and the cycle continues indefinitely.