Gundam Sentinel

Gundam Sentinel is a photonovel series, one of many Gundam side-stories taking place in the Universal Century timeline. Written by veteran Masaya Takahashi, it takes place during the final phase of Zeta Gundam and the early stages of Gundam ZZ in UC 0088. The story shows The Federation's efforts to stop an insurrection by elite Federation officers, former Titans calling themselves the New Desides. What's noteworthy about Sentinel is the debut of prolific mechanical designer Hajime Katoki, the artist behind other iconic Gundams in the franchise such as the V2 Assault Buster Gundam, Wing Gundam Zero Custom and the Gundam Unicorn. Sentinel is regarded as one of the most well known Gundam side-stories to have been published, and is usually noted by fans as being one of the most mature stories in the franchise.

Tropes associated with the Gundam Sentinel are:

 * Alice Allusion: ALICE is the AI installed on the S Gundam, and 'she' gradually gains self-awareness over the story.
 * BFG, Wave Motion Gun: FAZZ's hyper mega beam launcher, Z Plus and S Gundam's Beam Smartguns. The Z'od-iacok, a Mobile Armor over 200 meters in length, splits down the middle to reveal an absurdly huge beam cannon.
 * Civil War: The New Decides are Titans remnants.
 * The Federation: Actually being proactive for once!
 * Fun with Acronyms: Extraordinary Superior (Ex-S) Gundam. But that can't compare to "Advance Logistic & Inconsequence Cognizing Equipment (ALICE).
 * Heroic Sacrifice:
 * Humongous Mecha: It's the Gundam series...
 * Interquel: Although Gundam ZZ has already started by the time of this story.
 * Mecha Expansion Pack: It's this story that really introduces the concept into the Gundam world. The S Gundam has a booster variant (large boosters instead of legs) and the Ex-S Gundam is basically a stronger S. The FAZZ is this to the ZZ Gundam, and there's a Zeta Plus variant with heavy boosters attached.
 * On the opposite side, the Xeku Ein has at least 3 different mission configurations.
 * Punny Name: The villains of the story are a new group of anti-colony soldiers. In the Universal Century, colonies are grouped into clusters called "Sides" - hence, New Desides (De-Sides).
 * And then there's the Ex-S Gundam, which set the new gold standard in ridiculously overbuilt mecha designs.
 * Shout-Out: Members of New Desides are based on Shinsengumi. And Ryo Roots is based on Ryoma Sakamoto (='base', 'root').
 * Super Prototype: Played with - the FAZZ and Zeta Plus Mobile Suits are essentially production versions of the ZZ Gundam and Zeta Gundam.
 * The FAZZ was made as a testbed for the ZZ Gundam's Full Armor parts, before Judau got them in that series. In a subversion, the parts do work as planned, but because the MS itself was gutted for cost purposes (leaving out the FA parts' Anti-Beam Coating, for example), it's a worse unit overall. All three get destroyed on the moon.
 * The Zeta Plus, on the other hand, saw considerable service (mostly out of the spotlight) as a good, useful MS. The main S Gundam pilots even use them as trainer units, since they weren't given access to it at the time.
 * And then there's the Ex-S (Extraordinary Superior) Gundam, which both Katoki and Takahashi seemed to consider a Lightning Bruiser Game Breaker. Game depictions range from "useful" to "better than the Nu Gundam".
 * Theme Naming: Most of the characters are named after historical figures from the Bakamatsu period of Japanese history. The names tend to use the formula "Given name = direct Japanese-to-English translation, surname = part of the Japanese name changed to a close English homophone" (for example, Isami Kondo -> Brave Cod).
 * The Smurfette Principle: The only active female character is ALICE - and even she's S Gundam's AI without humanoid appearance.
 * Super Robot Wars: The S and Ex-S Gundams both appeared in SRW4 as cameo units. Several years after its release, fans hacked Alpha 3 and found half-completed sprites for Sentinel, leading to the theory that it was going to be in but was removed to make room for Gundam Seed.
 * hacking of Alpha 2 also shows the same incomplete data which shows that Seed was probably intend to be in alpha 2 and that Sentinel was removed earlier on the line.