Killing Time PC
Originally released in 1995 on the 3DO console as a first-party exclusive and then remade for PC, Killing Time is a run-of-the-mill Doom clone with a significant twist - a quasi-open-world setting in the form of an entire island trapped in stasis and filled with monsters from Egyptian mythology and zombified gangsters, flappers and estate staff. Essentially, the player shoots their way across each map searching for Keys and artifacts to unlock the secret of the estate, then re-visits some of the mansion's locations to reveal the final boss. Other than this, it's typical of what you'd expect from shooters of the era, though the Roaring Twenties setting is an refreshing diversion from the usual spaceships and energy guns of the era.
The GoG version is (as typical of their releases) hardly a technical marvel, with video and sound problems even on top of the awkward controls of the Prism Entertainment 2015 update. The most "authentic" way to play is probably with the 4DO emulator, which I tried a few years back, but even the slapdash GoG port was preferable to playing a 3DO game on an Xbox controller or keyboard. Regardless, it's playable from start to finish - which can certainly take some time. Initially I was a bit overwhelmed by the amount of hidden niches and branching pathways and even got a little stressed trying to memorize where I'd been, but it's not as bad as it seems once you revisit areas and realize there are actually very few alternate routes, many of which loop round into other areas you'll end up exploring anyway. You can also glean hints from the live-action FMV sequences that are quite cleverly integrated into regular gameplay, though these relate more to the background lore and core narrative than assisting player exploration.
There's not much of an arsenal - a revolver that can later be dual-wielded, tommy guns, a handful of magic ankhs, and molotovs, though ammo withstanding you'll probably opt for either the shotgun or flamethrower most of the time. Conversely, I was impressed by the amount of monster variety, though the most "supernatural" enemies like floating busts and skulls struck me as the silliest, even on an island of killer clowns and bloodthirsty chefs. At first the monsters seem to be chosen to match the theme of the different areas - young maids inside the mansion who fastidiously dust props until triggered to sprout giant fangs and wings, or oversized frogs in the sewers - but at times they seemed to haphazardly dump hordes of different enemy types wherever they felt like it. Unfortunately the different enemy types don't do anything to change how you approach combat beyond some being more irritating than others, to the extent that the only real strategy for any difficult situation is strafing in and out of cover. The only exception was the penultime boss, who respawns constantly throughout the mansion whilst taunting you with all the menace the game's low bitrate can muster.
Thus for all its visual and aural originality, you'll almost certainly tire of the brainless shooting galleries within a few hours and the odd puzzle or trap won't do much to keep players engaged. For this reason I can't really recommend the game as anything more than a novelty from the retro FPS days. Don't forget to smash that like button and subscr - Oh, nevermind.