You can certainly enjoy Half-Life: Alyx without playing the other games in the series, but you’ll definitely want to at least watch a story recap on YouTube if you want to get the most out of the game. The series has a rich, well written, and well-established lore that you don’t want to miss out on. Besides, the other games are considered some of the best of all time, so checking them out for yourself is a no-brainer regardless! It’s also worth noting that a lot of the jokes and references will only make sense with prior knowledge of the series.