The two games have similar base gameplay mechanics, wherein the player places troops of different classes to defend their crystals against multiple waves of enemies advancing across the screen.

The games use character designs and music created for Tactics A2 by artist Ryoma Itō and composer Hitoshi Sakimoto, and the series was produced by Takehiro Ando.

Square Enix was assisted in development of Guardians and Defenders by external studios Mobile Software Foundation and Winds.

Defenders was met with generally poor reviews, despite achieving one million downloads worldwide by 2012, with critics finding the game to be uninspired and unpolished.

All of the releases in the Crystal Defenders series are tower defense games composed of multiple stages, each consisting of a top-down view of a winding path.

[8] The Wii version of Crystal Defenders is divided into R1 and R2 chapters and offers a new ranking system via Nintendo Wi-Fi Connection.

The player can place troops on the squares on the right half of the map, defending against enemies entering from the left side of the screen.

[14] Different classes also attack in different patterns, with some reaching multiple spaces in front of them in a group or line, while others have special abilities such as the Paladin blocking enemies or the White Mage restoring health of other troops.

[1][2][16][3] The Crystal Defenders series uses the recurring setting of Ivalice, specifically recycling character designs and aesthetic elements from the Nintendo DS title Final Fantasy Tactics A2: Grimoire of the Rift.

[42] The game was re-released for iOS with higher quality graphics as Crystal Defenders Plus on February 20, 2013; W1 was made free with the other chapters available as in-app purchases.

Reaction to the presentation of the mobile versions of Crystal Defenders and its ports were mixed; Connor Egan of Slide to Play noted that it "faithfully reproduces the look of the Final Fantasy Tactics series", but found that the control scheme made the gameplay area feel small and cramped.

[55] Sam Bishop of IGN criticized the visuals of the PlayStation 3 port of the game for being "minimally animated" phone graphics with a border around them, though he praised the music.

[5] IGN's Ryan Geddes, in reviewing the Xbox 360 version, was much harsher: he dismissed the character designs as "generic looking" and the animation quality as "dull", though he had no complaints about the music or sound effects.

[56] Tom McShea of GameSpot had similar complaints about the Xbox 360 version, calling the character graphics "devoid of personality" with minimal animation.

The presentation was praised, with Levi Buchannan of IGN terming the graphics as "colorful and nicely drawn" and Torbjorn Kamblad of TouchGen calling it "colourful, bright and cute".