Survival mode is a video game mode in which the player must continue playing for as long as possible without dying in an uninterrupted session while the game presents them with increasingly difficult waves of challenges.
 A variant of the mode requires that the player last for a certain finite amount of time, after which victory is achieved and the mode ends.
 The mode is particularly common among tower defense games, where the player must improve the defenses of a specific location in order to repel enemy forces for as long as possible.
 Survival mode has been compared to the gameplay of classic arcade games, where players face off against increasingly stronger waves of enemies.
 This mode was intended to give the game a definite and sometimes sudden ending, so that other players could then play the arcade game as well.
Rithmomachy (or Rithmomachia, also Arithmomachia, Rythmomachy, Rhythmomachy, or sundry other variants; sometimes known as The Philosophers' Game) is a highly complex, early European mathematical board game.
 The earliest known description of it dates from the eleventh century.
 A literal translation of the name is "The Battle of the Numbers".
 The game is much like chess, except most methods of capture depend on the numbers inscribed on each piece.
Focus is an abstract strategy board game, designed by Sid Sackson and first published in 1964 by Kosmos.
 The game has been re-published many times since, sometimes under the titles "Domination" or "Dominio".
 "Focus" won the 1981 Spiel des Jahres and Essen Feather awards.
 The game appears in Sackson's "A Gamut of Games" in the section "New Battles on an Old Battlefield".
The Sega CD, originally released as the Mega-CD (メガCD , Mega-Shī Dī ) in most regions outside of North America, is an add-on device for the Sega Genesis video game console, designed and produced by Sega.
 It was released in Japan in 1991, North America in 1992 and in PAL regions in 1993.
 The device adds a CD-ROM drive to the console, allowing the user to play CD-based games and providing additional hardware functionality.
 It can also play audio CDs and CD+G discs.
 While the add-on did contain a faster central processing unit than the Genesis, as well as some enhanced graphics capabilities, the main focus of the device was to expand the size of games.
 Known for several games such as "Sonic CD" and for the controversy of violent video games including "Night Trap", the Sega CD sold 2.24 million units worldwide.
 It was officially discontinued in 1996.
A beer and pretzels game is any of a class of tabletop games that are light on rules and strategy, feature a high amount of randomness and a light theme.
 This is in direct contrast to Eurogames, which involve complex rules and emphasize strategy over randomness.
 The term was originally coined to describe relatively simple wargames that did not require extraordinary focus to play.
 The name was then adopted by gamers to mean casual, short and easy to play games in general.
 Examples of beer and pretzels games include "Bohnanza", "Wizwar" and "Pit".
Limb independence is a term commonly used by drummers to describe the coordination ability that is necessary for the physical multitasking of advanced drumming.
 Drummers use four limbs when they play.
 The left foot on the hi-hat (sometimes on another bass drum if double bass drums are used), the right foot on the bass drum, and the two hands on other cymbals and drums on the drum kit.
 Limb independence allows them to play different rhythms, without having to consciously focus on each one individually.
 This is especially important in jazz and latin based drumming.
 It is also one of the more difficult parts of learning the drums, since it is harder to process.
The Baker format in Ten-pin bowling is the cornerstone of team play because each player contributes frames to a single game.
 A single player on a 5-person team would bowl frames 1 & 6, 2 & 7, etc.
 To bowl a perfect Baker 300, all 5 players have to throw two strikes each and the final bowler, or "anchor", having to throw the two fill frames in the 10th for a total of four.
 Only a handful of Baker 300 games have been shot which is made more difficult as games in NCAA bowling are played on sport compliant patterns.
Ender's Game is a 1985 military science fiction novel by American author Orson Scott Card.
 Set in Earth's future, the novel presents an imperiled mankind after two conflicts with the "buggers", an insectoid alien species.
 In preparation for an anticipated third invasion, children, including the novel's protagonist, Ender Wiggin, are trained from a very young age through increasingly difficult games including some in zero gravity, where Ender's tactical genius is revealed.
An adventure game is a video game in which the player assumes the role of protagonist in an interactive story driven by exploration and puzzle-solving.
 The genre's focus on story allows it to draw heavily from other narrative-based media, literature and film, encompassing a wide variety of literary genres.
 Many adventure games (text and graphic) are designed for a single player, since this emphasis on story and character makes multi-player design difficult. "
Colossal Cave Adventure" is identified as the first such adventure game, first released in 1976, while other notable adventure game series include "Zork", "King's Quest", "The Secret of Monkey Island", and "Myst".
Play (: "Jiāyòng Diànnǎo Yǔ Yóuxì"literally: "Home Computer Game" ) was a Chinese game-and-software oriented magazine founded in October 1993 and first officially published in June 1994 by Popular Science Press (科学普及出版社; Kēxué Pŭjí Chūbănshè).
 The magazine was originally named Jiāyòng Diànnǎo Yǔ Yóuxìjī (家用电脑与游戏机; lit.
 "Home Computer and Game Console"), and focused on both PC games and console games.
 In January 2001 it was renamed to its current name and its coverage shifted to focus on PC games exclusively, making it the first specialized PC gaming magazine in China.
 Subsequently "Play" became one of the most important gaming magazines in mainland China.

Question: Are Rithmomachy and Focus both difficult games to play?
Answer: yes