I honestly 100% expected an Indiana Jones joke the entire time. Bit disappointed but also pleasantly surprised.
I liked the alien's design and the animation itself was quite nice. I think the atmosphere was very well set at the start with the birds and his reaction to them illustrating that there are dangers in this world, but that he is somewhat used to them. It's infinitely more compelling to watch him discover something terrifying that way, cause you know he's not completely helpless but he has his limits. That and it makes him a bit more realistic and relatable. It actually totally tricks you when he powers up his backpack blaster, giving the moment that much more tension. The fridge itself had a really cool monster design and you used some pretty fun and classic horror angles with this, like when he was circling the fridge and when it sprouted legs. Just feels like something out of a monster flick. The ending was a bit out of place, honestly, the whole artstyle switch just seemed to kinda come out of nowhere. Maybe if it was made just a bit weirder/scarier it would have felt more justified. Otherwise I liked it.
Keep it up, and if you tag this with halloween2019 you can participate in the Newgrounds Spooktacular.