I feel like a good place to start (or at least get to early on) is to implement moods which are actually built-in to a media player, such as MusicBee. the list from the config file:

• Angry
• Bewildered
• Bouncy
• Calm
• Cheerful
• Chill
• Cold
• Complacent
• Comatose
• Crazy
• Crushed
• Cynical
• Groovy
• Depressed
• Dreamy
• Drunk
• Eclectic
• Emotional
• Energetic
• Envious
• Happy
• Mellow
• Morose
• Quirky
• Rockin
• Sad
• Soothing
• Spooky
• Sunday Brunch
• Tranquil
• Trippy
• Upbeat
• Wild
• Work

yes, many of these probably aren't actually "Moods", but since they're built into a media player, they're probably worth considering.