Sentinel Returns

Sentinel Returns is a video game developed by Hookstone, produced by No-Name Games and published by Sony (under the Psygnosis label) in 1998, for PC and PlayStation. It is the sequel to The Sentinel by Geoff Crammond and features 651 levels, a multiplayer mode and a soundtrack (titled "Earth/Air") composed by John Carpenter and arranged by Gary McKill.

The PC version has native support limited to a software display mode and an accelerated Glide mode, because in 1998, 3DFX cards were the de facto standard for gaming 3D graphics. However, modern computers can run the game in accelerated mode with the wrappers dgVoodoo or OpenGlide, which translate Glide calls respectively into Direct3D or OpenGL calls.

This game looks very different from its predecessor. While in The Sentinel the levels were bright and colorful, in Sentinel Returns they are dark and gloomy, with flashes of light being emitted when an object is created or absorbed, and the mouse pointer dynamically lighting the world. The game has a general "hallucinated" look: the skies are made out of contrasting streaks of color; the trees look like sperms; the boulders breathe and have a sphincter on the top; the sentinels and sentries are hybrids of flesh and metal; the sentinel stands are covered with skin and have four vertebral columns protruding from the corners; the "specimen" representing the living part of the synthoid resembles a hydatidiform mole, and it squirms and lets out a shriek when injected with a needle.

Game mechanics
This game plays very much like its predecessor: for this reason, only the differences between them will be discussed here.
 * The action is faster and the movements (rotating the synthoid and transferring the consciousness from a synthoid to another) happen in real time. This allows the player to move much more quickly across the landscape and to complete a level in far less time. To counterbalance this, the Sentinels and Sentries (which have a FOV of 28 degrees) are able to absorb energy from the synthoid at a much greater rate.
 * By absorbing a sentry, a tree is created in a random square in the level.
 * There are "only" 651 single player levels, while there were 10000 in the first episode. For this reason, it is only possible to skip up to 4 levels when one is finished. In particular, the player will skip: 4 levels by absorbing from 90% to 100% of the energy in the level; 3 by absorbing from 70% to 89% of energy in the level; 2 by absorbing from 50% to 69% of energy in the level; 1 by absorbing less than 50% of energy in the level.
 * A multiplayer mode is present. To start a multiplayer match on the PC version, the host needs to set up the random creation of a level, choose a DirectPlay service provider, type a host name and a player name, and finally select "Host a Session". Every guest needs to select the same service provider and select "Join a Session". The goal of multiplayer mode is to race each other to the Sentinel; every player can teleport each other's synthoid to lower levels. The supported DirectPlay service providers are IPX, TCP/IP, modem and serial.
 * The game has two endings. To see the first one, the player must beat the 651st level. To see the second one, the player must beat every level, or "achieve 100% orchid", as this is expressed in the game.

Graphical differences between PC and PlayStation version
Although their gameplay is almost identical, the two versions have several differences in their graphical look.
 * The level selection and level loading screens are fully polygonal in the PC version, while they are made out of 2D elements in the PS1 version.
 * The 3D models have more polygons in the PC version than in the PS1 version.
 * The PC version has colored lights (although only with the hardware accelerated rendering), the PS1 version does not.
 * The levels have different architectures in the two versions.
 * The checkerboard patterns are more evident in the PS1 version, which has also rougher-looking slopes than the PC version.
 * The skies have orbiting planets in the PS1 version, they do not in the PC version.
 * When an object is created in the PC version, it appears abruptly. In the PS1 version, a seed (when a tree is created) or 2/3 "energy clusters" (when a boulder or a synthoid is created) fly to the selected square, while rotating polygons assemble into the object.
 * When an object is absorbed in the PC version, it disappears abruptly and generates a number of "energy rings" which quickly disappear. In the PS1 version, it disassembles into rotating polygons, while a seed (when a tree is absorbed) or 2/3 "energy clusters" (when a boulder, a synthoid or a sentry is absorbed) fly to the player's POV.
 * The explosion of the sentinel is seen from the player's POV in the PC version and as a non-interactive scene in the PS1 version.
 * After a level has been beaten in the PC version, a vortex made of a spiral and a number of triangles appears above the sentinel stand; in the PS1 version it does not, but is mentioned anyway in the manual.
 * In the level-ending hyperspace scene, in the PC version the POV looks up into the vortex, while it looks down toward the synthoid in the PS1 version.