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Bugs:Hover! (1995)

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This page details bugs of Hover! (1995).

Collision Detection

Problematic car collision body

To realize the ellipsoid shape of cars, two spheres are used:

  • One smaller sphere at the tip of the car.
  • One bigger sphere at the rear of the car.

However, the spheres do not fully touch each other, leaving a very small gap between them in which no collisions happen. Due to this, the following is possible, which may be experienced even accidentally when gliding sideways during normal gameplay (especially at the hard car control setting which removes almost no traction when turning sideways):

  • Drive through other objects (e.g. a robot car) without touching them.
  • Get stuck in a wall. Graphics are glitchy as you are constantly behind and in front of the wall (as the camera is centered between the spheres). This is possible in two ways:
    • Glide into walls ending in an exterior sharp angle (the sharper, the easier). You can find several in the Hip City (2nd) level. Especially easy with temporarily placed power-up walls as no second wall may prevent the bug from happening by pushing you away again.
    • Drive very close sideways to a wall, bring the car to a halt, and then turn. Since no collision detection is done when just turning (without any traction). If you then try to move forward, your rear car sphere is already behind the wall, and will pull you into it.

Erroneous multiple collision resolval

The problematic corner in level 3.

If you drive into a corner ending in a sharp interior angle at high speed, you may easily end up in one of the walls (typically the one you were closer to).

This is only really possible in the Sewer (3rd) level, in the small area locked behind 3 glue pads (often housing a blue and red flag). The small area behind the stairs to the left of it ends in a very sharp corner. Driving towards it from the mossy wall and turning towards it shortly before hitting the corner easily pushes you out of the maze, even through the mossy wall. It is also easy to kick opponent cars into the wall here.

This is probably happening due to failure in resolving multiple collisions happening in one frame, ignoring one of them.

Unsolid ceilings

Almost all ceilings which were deemed "unreachable" under normal gameplay are not solid and can be jumped or fallen through. This typically does not apply to ceilings of a raised platform you can drive on. You can reach them by placing a wall, jumping on it, placing another, and repeating the steps until you gain enough height. Note that you cannot jump on walls placed on a raised platform you can drive on, as you will simply fall through them.

Out of bounds oddities

These bugs are neglectible, as the original game claims to only support coordinates between 0 and 23000 on the X and Y axis, but may be experienced accidentally due to breaking out of the maze because of the buggy collision detection (s. above). The area outside these coordinates typically behaves glitchy, depending on where you escape it:

  • Negative X axis: Driving too far results in hitting an invisible wall, and being pushes back more closer to the maze on the X axis. There is no invisible wall, but collision detection fails at very small coordinates and yields the buggy outcome.
  • Positive X axis: Driving here results in collisions ceasing function. Placed walls or robot cars which escaped with you simply makes you drive through them. Driving further overflows to negative X coordinates and causes you to move towards the maze again from the opposite side.
  • Y axis: This axis crashes the game, as it apparently overrides a vital variable following in the CPlayer structure. Typically, one Y side has some space before over- or underflowing, while another almost crashes immediately outside of the maze, due to the mazes built so closely to them.
  • Positive A (Z / height axis): At heights around 30 times of the maze, trying to jump further makes the car bump against a non-existent ceiling. Graphics of placed walls start to glitch, and you often fall through them. These heights are normally unreachable as you cannot collect more than 9 walls for your journey, but you need at least 60.

The graphics are also slightly messy:

  • Noticably, the background graphics actually repeat below ground level, making it seem like you're driving a damn good hovercraft this time.
  • The outside of the Sewer (3rd) level is actually a wall texture repeated multiple times. It may display some lines of garbage near the horizon in the low-resolution fullscreen mode on some systems due to unknown reasons (apparently, the texture data is ending too early).
  • Moving too far on the X axis causes the mini map to draw bogus lines spanning over its whole display. The triangles of cars can also wrap over and are seen apparently driving further away in unreachable space.