Photoelectrowetting is a modification of the wetting properties of a surface (typically a hydrophobic surface) using incident light.
 Whereas ordinary electrowetting is observed in surfaces consisting of a liquid/insulator/conductor stack, photoelectrowetting can be observed by replacing the conductor with a semiconductor to form a liquid/insulator/semiconductor stack.
 This has electrical and optical properties similar to the metal/insulator/semiconductor stack used in metal-oxide-semiconductor field effect transistors (MOSFETs) and charge-coupled devices (CCDs).
 Replacing the conductor with a semiconductor results in asymmetrical electrowetting behavior (in terms of voltage polarity), depending on the semiconductor doping type and density.
A "Christmas tree" was a type of alert area constructed by the United States Air Force for the Strategic Air Command (SAC) during the Cold War.
 Oftentimes, bombers or tanker aircraft were stationed next to a readiness crew building (RCB), also known as "mole hole" facilities.
 The alert apron, also known as an alert ramp, received the name "Christmas tree", because in planform it resembled a tree of the same name.
Many electrical devices use direct current (DC) power, often provided by an AC (alternating current) to DC adapter, also known as a "wall wart" or "power brick".
 The adapter typically supplies power to the device through a thin electrical cord which terminates in a coaxial power connector often referred to as a "barrel plug" (so-named because of its cylindrical shape).
 The polarity of the adapter cord and plug must match the polarity of the device, meaning that the positive contact of the plug must mate with the positive contact in the receptacle, and the negative plug contact must mate with the negative receptacle contact.
 Since there is no standardization of these plugs, a polarity symbol is printed on the case indicating which type of plug is needed.
Cell polarity is a fundamental feature of many types of cells. Epithelial cells are one example of a polarized cell type, featuring distinct 'apical', 'lateral' and 'basal' plasma membrane domains.
 Epithelial cells connect to one another via their lateral membranes to form epithelial sheets that line cavities and surfaces throughout the animal body.
 Each plasma membrane domain has a distinct protein composition, giving them distinct properties and allowing directional transport of molecules across the epithelial sheet.
 How epithelial cells generate and maintain polarity remains unclear, but certain molecules have been found to play a key role.
Polarity is a board game that requires strategic thinking and dexterity to control hovering magnetic discs.
 "Polarity" was invented in 1985 by Canadian artist and designer Douglas Seaton.
 It was first published in 1986.
 The game has had a tumultuous past, with its rights changing hands several times over the past two decades.
 The game has been published by Telemotion Technologies, Irwin Toy, briefly with Mattel and most recently by Temple Games.
 The game ships in a canvas sleeve and include the magnets, the board, and a paper rulebook.
 An unrelated game of the same name is published by a company called Mindwalk (Company).
The visual N1 is a visual evoked potential, a type of event-related electrical potential (ERP), that is produced in the brain and recorded on the scalp.
 The N1 is so named to reflect the polarity and typical timing of the component.
 The "N" indicates that the polarity of the component is negative with respect to an average mastoid reference.
 The "1" originally indicated that it was the first negative-going component, but it now better indexes the typical peak of this component, which is around 150 to 200 milliseconds post-stimulus.
 The N1 deflection may be detected at most recording sites, including the occipital, parietal, central, and frontal electrode sites.
 Although, the visual N1 is widely distributed over the entire scalp, it peaks earlier over frontal than posterior regions of the scalp, suggestive of distinct neural and/or cognitive correlates.
 The N1 is elicited by visual stimuli, and is part of the visual evoked potential – a series of voltage deflections observed in response to visual onsets, offsets, and changes.
 Both the right and left hemispheres generate an N1, but the laterality of the N1 depends on whether a stimulus is presented centrally, laterally, or bilaterally.
 When a stimulus is presented centrally, the N1 is bilateral.
 When presented laterally, the N1 is larger, earlier, and contralateral to the visual field of the stimulus.
 When two visual stimuli are presented, one in each visual field, the N1 is bilateral.
 In the latter case, the N1's asymmetrical skewedness is modulated by attention.
 Additionally, its amplitude is influenced by selective attention, and thus it has been used to study a variety of attentional processes.
The universal motor is so named because it is a type of electric motor that can operate on AC or DC power.
 It is a commutated series-wound motor where the stator's field coils are connected in series with the rotor windings through a commutator.
 It is often referred to as an AC series motor.
 The universal motor is very similar to a DC series motor in construction, but is modified slightly to allow the motor to operate properly on AC power.
 This type of electric motor can operate well on AC because the current in both the field coils and the armature (and the resultant magnetic fields) will alternate (reverse polarity) synchronously with the supply.
 Hence the resulting mechanical force will occur in a consistent direction of rotation, independent of the direction of applied voltage, but determined by the commutator and polarity of the field coils.
Polar overdominance is a unique form of inheritance originially described in livestock, with relevant examples in humans and mice being discovered shortly after.
 The term polar is used to describe this type of overdominance because the phenotype of the heterozygote is more prevalent than the other genotypes.
 This polarity is shown as differential phenotype is only present in one of the heterozygote configurations when the recessive allele is inherited in a parent of origin type fashion.
 Polar overdominance differs from regular overdominance (also known as heterozygote advantage) where both heterozygote genotypes display a phenotype that has increased fitness regardless of the parent of origin.
 Studying this type of inheritance could have practical applications in preventative medicine for humans as well as a variety of other agricultural applications.
Master Man was a Kid Eternity villain who made his first appearance in "Kid Eternity" #15.
 He is a type of reverse polarity Kid Eternity, similar to the way Ibac is to Captain Marvel.
 Kid Eternity's opposite number, Master Man was given powers similar to the Kid's by a figure heavily implied to be the Devil.
 When Master Man said "Stygia", he could summon any evil historical or mythological figure from Stygia.
 He was an average sized man with black hair, who wore a green cape and a military type uniform with a Skull and Crossbones on the front.
 He was also a smoker.
 Master Man was sent by the being who gave him his powers to spread evil on earth.
 He summoned Rasputin to help him cause a jailbreak, but Kid Eternity prevented this.
 Master Man then captured Kid Eternity and summoned Torquemada to cause the Kid such pain he would request eternal death.
 However the Kid freed himself.
 Master Man summoned up Batu Khan but the Kid summoned Charles Martel who defeated the Mongol.
 As Master Man tried to escape the shadowy figure caused the ground to open, sending him into fire.
Space Alert is a team survival designer board game created by Vlaada Chvátil in 2008.
 Players assume the roles of space explorers on a mission to survey the galaxy.
 The crew is evaluated on teamwork and how they deal with problems that arise on their journey.
 It was given a special prize for "New Game Worlds" in the 2009 Spiel des Jahres awards.

Question: Polarity and Space Alert, are which type of games?
Answer: board