engaging
Very interesting and fun so you want to keep paying attention.
Engaging means capturing and holding someone's attention in a way that makes them want to stay involved. When a book is engaging, you find yourself reading “just one more chapter” because the story pulls you in. An engaging teacher makes lessons interesting enough that students actually look forward to class instead of watching the clock.
The word suggests active involvement: something engaging draws you in and keeps you thinking, participating, or feeling connected. A museum exhibit might be engaging because it lets you touch things and solve puzzles rather than just reading signs. A conversation becomes engaging when both people are genuinely interested in what the other is saying.
You can also use engage as a verb: a speaker might engage the audience by asking questions or telling surprising stories. When you engage with a subject, you're actively working to understand it rather than just passively listening. Notice that engagement requires something from both sides: the engaging thing must be interesting, and you must be willing to pay attention and participate.