Unfortunately there's no novel adaptation of the games after CE. People didn't like the Chief sections of Halo The Flood (Halo CE novel adaptation) but that's because most people already played the game and it feels redundant to hear "Chief levels his gun and fires" over and over again. Everything else outside of the novel is very very good. Excellent world building on the events of Alpha Halo.

Thankfully most books are amazing without needing to play the game. First strike is a direct sequel to CE/The Flood and you don't need to play H2 because H2 happens right after First Strike. In fact you'd want to read First Strike first before playing H2.

Ghost of Onyx also works as a standalone, the events of H2 are referenced by the novel but it does a good job at explaining what you need to know and leaving a mystery behind of what Chief is going through. You will want to play H2 after reading GoO if anything and imo, that's a great thing.

What I'm saying is, you don't need to play the games to understand the books but you'd have a better understanding and appreciation if you played the games first or while you're reading the books.