Marathon 2 by Bungie also had weird non-euclidean maps with overlapping sections in the late 90s I think.

I miss the customizability of that game. Early bungie works were up there with early blizzard or early valve. They sold a tool for fun instead of casting a bait for profit.

Do you know anything about Prey 2017’s “looking glass”? Do you know if it involves any special techniques?

I know nothing about this stuff, but when I saw in-game I was really impressed. You can even break the screens into shards, and the little pieces still maintain the effect when they’re lying on the floor or flying through the air.

> But certainly the game Portal (2007) hyped using portals for rendering prior to Prey.

They were referring to Prey (2006).

Original Descent was software rendered though.

> Fun fact: the creator of the DF engine told me he based it on a reverse engineering of a beta release of DOOM.

Can you provide a source? As I understand it DF is based on the (pre release?) Tie Fighter engine, and DF began production before Doom released. That's why for example DF has some non-textured 3D models like the turrets and mouse droids. I follow The Force Engine (reverse engineered fan port) and Dev Game Club (hosts worked at LA).

Supposedly DF devs did see Doom (perhaps even a pre release version), but already had their own tech working by that point.

> Apparently, the final release of DOOM cut a lot of engine features to gain speed.

Doubt. There's a lot of interviews with the ID guys, and I don't recall anyone saying they cut significant technical features. They made Doom in only 13 months, minus almost a month to port Wolf3D to SNES. Maybe Carmack -- or the released alphas and betas -- can clarify? Or perhaps you are confusing some of the Doom porting efforts, which did cut down levels and sometimes features significantly.

Pretty sure water was just a teleporter? You may be thinking about the mirror effect? I think that was a kind of a portal effect. You had to make a large empty section behind each mirror that was used by the engine to render a mirrored copy of things in front of the mirror.

You could make some weird impossible geometries by just superimposing sections. Two sections could occupy the exact same coordinates, but movement and rendering were done across edges shared by sections and did not care about if there was some other section in the same space. As long as there was never a way to see those sections at the same time.

E2L11 “Lunatic Fringe.” The map has an outer ring containing 720 degrees of hallway. Surprisingly disorienting even when you know that’s what’s going on.

I'm thinking it's likely the number of supported colors and integer vs floating point precision.

You'll notice that quake textures are very similar to PS1 textures in that they are pixelated and use a limited number of colors, whereas N64 textures have more of a smooth gradient.

Likely also there are differences in the lighting systems as well. This is why I think people compare Quake II or even Quake III Arena to UE1. The OG quake really was a hack just to be the first that did 6 degrees of freedom textured 3D graphics on a PC, which I think they were the first for those exact constraints. My history is a little fuzzy, SEGA certainly had them beat by multiple years on arcade boards but those were all custom, and other games that had 6 degrees of freedom were not textured. It was a busy time !

Newer temporal rendering techniques result in lower quality frames and output when the prevailing art style of the game is not one that is photorealistic.

There's a lot of "smearing" as a result. It's not just you, it's how newer rendering techniques in the Unreal Engine end up being perceived by most people.