This map is in the style of that base in the middle of the forest in HL2: EP2. The White Forest and that base are my favourite areas in the Half-Life series. Station 51 captures the feeling of them perfectly, making you feel like you’re pretty high above the forest in a (kind of) abandoned base. There’s fights with zombies and Combine, but mostly Combine. It is linear in some places but has some wide open areas, which might not suit your tastes but I didn’t mind. There are some parts requiring you to find a hidden passage but they were pretty easy and I found all of them instantly. I had a lot of fun with this map.