Hi Victor! Thanks for the great feedback.
To customize the player, I removed all the menu items, slide titles, and UI buttons. Here's a tutorial on how that works:
https://community.articulate.com/series/articulate-storyline-2/articles/customizing-the-playerOnce you strip everything out, it's a good idea to save your player so you can easily access it in the future.
You can also download some pre-built players:
https://community.articulate.com/download/10-pack-of-seamless-storyline-player-skins It looks like those may still have the background but it's a good start to removing everything.
Let me know if you have any further questions!