tantalizingly
In a way that tempts you with something just out of reach.
Tantalizingly means in a way that tempts or attracts you while staying just out of reach, making you want something even more because you can't quite have it yet.
When a mystery novel drops tantalizing clues, it gives you hints that make you desperate to know what happens next, but it keeps the answer hidden just a little longer. A bakery might release tantalizingly delicious smells onto the street, making passersby want to come inside. Or imagine watching the last five minutes of an exciting game tick by tantalizingly slowly when your team is winning by just one point.
The word captures that specific feeling of wanting something that's close enough to seem possible but not quite yours yet: a wrapped present sitting tantalizingly under the tree before your birthday, a difficult puzzle with a solution that feels tantalizingly close, or the last chapter of a book you're saving for later. The closer and more possible something seems, the more tantalizing it becomes.