Spaceship Shenanigans

Summary

This game resembles the arcade game Missile Command, and tests distribution and shifting of attention, and the effect of multimodal (auditory and visual) stimuli.

Premise

The WSS White Giant is under attack! It is your job as Tactical Officer to guide the defense system to aid your fighters in shooting down incoming squadrons of enemy Wasp aircraft as well as colony against the attacks from the Wasp commander itself.

Objective

Protect the WSS White Giant, destroy all enemy Wasp aircraft, and defeat the Wasp commander.

Characters

Cheetah C-24 Fighter: See Meteor Madness

WSS White Giant: The colony that needs to be defended. It is armed with a Mobile Laser Defense Turret (MLDT) as its primary means of defense. It also gets support from the various C-24 fighters it carries.

Wasp Fighters: Basic Wasp aircraft. They attack WSI ships in waves and kamikazi into the colony to take out its defenses.

Cargo Box: This rewards resources and warps in right next to the colony.

Wasp Commander: Enemy commander who's impervious to almost all attacks. After the main Wasp force fails, directly assaults the colony.

Gameplay

Colony Defense

The player defends the WSS White Giant, the Colony, in the center of the screen, floating somewhere in space. This colony is armed with a mobile laser defense turret (MLDT) capable of firing charged lasers from the colony to the edge of the screen. The MLDT hovers around the edge of the colony and sweeps clockwise (right arrow) or anticlockwise (left arrow) along the circular defense perimeter.

One issue with placing the base in the centre of the display rather than at the bottom of the display is that it could complicate the detection of brain electrical potentials: stimuli from the top half of space are processed in the inferior occipital lobe whereas stimuli from the bottom half of space are processed in the superior occipital lobe, so we will be recording voltages with grossly different scalp distributions and will be unable to average them together. We could go this route if it distinctly improves game play, but the price that we pay for this flexibility is that we will need double the amount of game play in order to achieve sufficient numbers of trials for successful data analysis, since we'll have to analyse targets in the upper and lower visual fields separately.

As game play progresses, various enemy alien aircraft, Wasps, appear from off screen and dive at the colony in the center of the screen in an attempt to destroy it. Later on in the game, friendly ships, C-24 fighters, will appear from off screen as well, though less frequently. They will then begin to assist in the attack on the enemy alien aircrafts, which will fight back against the C-24s.

In addition to enemies, cargo boxes appear. Cargo is warped in directly next to the colony. When this is about to happen, a cue signal is sent out by the colony letting the player know from what direction the cargo will appear.

Shooting

Releasing the spacebar fires the turret laser. Pressing the spacebar will stop the ship and holding the spacebar down will charge up the laser to increase coverage area. There is no cooldown on the laser. The laser shoots to the edge of the screen.

When you write "stop the ship," to what ship are you referring?

In what way is the laser's coverage area increased? If the beam widens, could this widening interfere with the measurement of reaction time, for example in a case where a target warps in within the wider coverage area so that no movement of the turret is necessary?

Cargo

In every stage, a cargo box materializes on the defense perimeter every 5 to 10 seconds since the last one was collected or warped out. It will appear either to the left, right, above, or below the colony. An early-warning system activates a stimulus in one of three different conditions of sensory modality:

Unisensory Visual

Display a large, 10 hz (50% duty cycle) flashing arrow at the center of the colony. The arrow appears either 100 ms (one flash) or 800 ms (eight flashes) prior to the materialization of the cargo and remains until the cargo materializes.

The early-warning system is fallible. 20% of the time, it indicates a sector 180º away from the cargo's actual sector.

This aspect of the task combines a variation of a centrally cued Posner attention paradigm (testing effects of cue validity and cue-target onset asynchrony) (Posner et al. 1987).

Multisensory Audiovisual

The arrow is accompanied by a klaxon (100 hz square wave modulated at 10 hz in synchrony with the arrow).

Unisensory Auditory

The klaxon alone.

I'm uncertain whether this makes sense since, with only two speakers, we can't achieve the same directional specificity with the klaxon as we can with the arrow, and since with three conditions we'll need 50% more trials overall to get enough observations of each condition.

The player has until 800 ms after the cargo materializes before it warps out. The player presses the "G" key to grab the cargo using the grapple beam.

Why the 800 ms absolute time limit? This could lead to frustration. Is there a way to motivate the player to react quickly that would still provide the player something instead of nothing if (s)he takes longer than 800 ms? Also, regarding the 'G' key, requiring the player to move their finger to a small key distinct from the key that the player uses for other functions is going to increase reaction time very markedly. Is there a reason for not using the up-arrow key, as Maritime Defender does for the wormhole connections?

This aspect of the task is a test of multimodal (audiovisual) integration. (Senkowski, Molholm, Gomez-Ramirez, Foxe)(auditory_visual_integration_2006.pdf)

Phases

Phase 1

Enemy ships fly in from off screen, toward the base. Enemy ships might vary their path slightly and move at a constant speed. Enemy ships aim to crash into the perimeter to weaken it, which will result in fewer bonus resources for the player due to the need to repair the damaged colony. (This amount of decrease will be determined along with the Colony Simulator design.)

If an interesting game can be implemented without path variation, that probably would be most desirable. Otherwise it may be difficult to ascertain what the player is reacting to at any particular time, for example if a meandering enemy moves from one defence sector to another.

Stage 1

1 enemy ship spawns 2 seconds after the player clicks 'Start'. Enemy ships spawn one at a time 2 seconds after the previous ship is destroyed. A total of 10 enemy ships will spawn.

Not exactly two seconds every time -- we need a small amount of jitter in the interval -- see the section of "Important Neuroscientific Considerations..." that's headed "For repeating events...."

Stage 2

2 enemy ships spawn 2 seconds after the player clicks 'Start'. Enemy ships spawn two at a time 2 seconds after the last visible ship is destroyed. A total of 20 enemy ships will spawn.

Stage 3

1 enemy ship spawns 2 seconds after the player clicks 'Start'. Enemy ships spawn one at a time every 3 seconds. A total of 10 enemy ships will spawn.

Stage 4

2 enemy ships spawn 2 seconds after the player clicks 'Start'. Enemy ships spawn two at a time every 3 seconds. A total of 20 enemy ships will spawn.

Phase 2 (Distractor Session):

Friendly ships (distractors) fly in from off screen and orbit the base. Friendly ships fire at enemy ships every 3 to 4 seconds. Enemy ships fire at friendly ships every 3 to 4 seconds. When completing the game, the more friendly ships left alive, the more resources awarded. (This amount will later be determined along with the Colony Simulator design.) This is a positive incentive.

Reaction time within this paradigm measures the player's ability to distribute attention across a broad field in the presence or absence of distractors.

Phase 2 repeats the same stages as phase 1 in regards to enemy spawning.

Friendly ships spawn 20% of the time each enemy spawns. A friendly ship can randomly spawn in any of the four quadrants with equal chance.

Boss Battle

Based on the basic five-box test from J. Townsend et al. - Brain Cognitive Research II.

After enough(?) waves of Wasps have been destroyed, the Wasp commander appears above the colony and starts to attack it. The Wasp commander is a large floating head with several eyes (5 or 7), sharp pointy teeth, and antennas that the commander shoots lasers at the colony and MLDT from. The player must continue to use the MLDT in order to drive away the Wasp commander while dodging the laser blasts it emits.

In order for the player to actually be able to damage the commander, they must shoot at its weak point: one of its eyes (the attended location). The vulnerable eye will be colored slightly different from the others which will let the player know that that is their target, all other eyes simply pose as distractors since a successful shot at one does nothing to the commander. Only one eye opens at a time (the stimulus). When the player fires the laser, it will automatically aim at the target eye. When no stimulus is visible, the MLDT fires at the impervious exoskeletal armor of the commander, essentially doing nothing.

Scoring

Cash is awarded for each Wasp destroyed in any phase. Bonus cash is awarded for collecting cargo boxes. A special cash bonus is awarded for defeating the Wasp commander at the end of the level. (The actual values of the cash will be determined along with the Colony Simulator design)