Blake Stone: Aliens of Gold
I took a bit of a break from my old-school FPS run but got back into it. This was a bit too old, though. I'm assuming it used the original Wolfenstein 3D engine because it largely looked and felt the same. Same basic format with 6 episodes each with 10 missions plus a secret. All the maps are variations of on a 2D square. No angles so all walls are 90 degrees.
This game does more than Wolfenstein 3D did. A lot more enemy types. A few more guns. In addition to health pick-ups there are food dispensers that take money. There are undercover friendly scientists that you aren't supposed to kill. Your default weapon is silenced so there is a tiny bit of stealth. Some enemies are hidden and come to life when you shoot the environment. They had some doors that automatically open to add a bit of difficulty.
But, some of those things didn't play out well. The friendly scientists would get in the way and block hallways and love walking in front of your shooting. Food dispensers weren't really necessary since there is more than enough health pickups. The silenced gun was inconsistent with damage so you'd usually just alert the guards anyways. Automatic doors were rarely used. While there were more guns, they all share the same ammo pool, so you mostly use the strongest gun (although ceiling turrets couldn't be damaged with the strongest gun, so there was some 'strategy' there).
The level design was better than Wolfenstein 3D. Instead of entrance/exit, you had one elevator that you needed to find a passkey to get to the next floor. You could return to previous floors (although they never really built on this and only once did you do something on a later floor that affected a previous floor). I did appreciate that the levels felt a bit lived in. For example, one floor was a cafeteria for the space station. So they put a bit of thought into the level design.
I played on the hardest difficulty, which was a bit of a mistake. The enemies feel a bit bullet spongey, so you basically only could use the best weapon. That made the early levels the hardest since you had weak weapons early on. The game has the same secrets as Wolfenstein 3D were you just headbutt the walls with no visual clues to find one. And the map designers had an awful habit of making secrets within secrets within secrets. And since most of the secrets just gave you treasure for a high score, there wasn't much incentive to search for them. That got boring fast and just found some maps online to find the secrets.
tl;dr - They did a lot more with the same engine as Wolfenstein 3D. It's a far better experience. But there's really no reason to go back and play this era of FPS.