Until recently, Articulate Storyline courses started with a black slide with a big start button. As of the July 2021 release, you can add a custom course thumbnail image to show on the start screen. And if you have a video in your course, you can set a poster frame–the image that shows until the video starts.
Check out this video I created for ATD Toolbox Tips on how to make a great first impression with these two features.
Update: It looks as though ATD’s YouTube channel has moved. You can find all the toolbox tip videos here: https://www.td.org/videos/toolboxtips