Totally not strange. I'd say it's typical and predictable.
I've been following IFs community for a long time and I see that about 95% of authors disappear without a word after some time. I suppose it's because they are beginners who were excited to make the game, but when difficulties arise their enthusiasm fades. I kind of understand them and respect that they tried (creating interactive game is damn hard thing imo), but annoys me that hardly anyone deigns to inform fans they are giving up the project. It's not right if they made their WIPs public and found followers.