- "The answer is simple. It's because I am the destroyer of all. I have accepted that."
- ―His answer when Bill Goldy telling him
Kamen Rider Dark Decade (仮面ライダーダークディケイド Kamen Raidā Dāku Dikeido?) is an evil version of Kamen Rider Decade that appear in the game Kamen Rider: Climax Heroes. Like Decade, he uses Kamen Ride Cards and transforms in the nine previous Heisei Main Kamen Riders.
Kamen Rider Dark Decade
Like Decade, Dark Decade can transform into any previous Kamen Rider with access to that respective Rider's powers and weapons.
Complete Form is the true form of Dark Decade that is able to manipulate the power of other Riders' final forms, accessed through the K-Touch. He wears the Dark Decade Complete Kamen Ride Card on his helmet, embedded in the Dark Decade Crown, and the others' Kamen Ride Cards on his chest.
Kamen Ride Forms
Through the Kamen Ride and Form Ride cards, Dark Decade can transform into any of the default forms of the primary nine Heisei Era Kamen Riders.
- Kamen Rider Kuuga (Mighty Form)
- Kamen Rider Agito (Ground Form)
- Kamen Rider Ryuki
- Kamen Rider Faiz
- Kamen Rider Blade (Ace Form)
- Kamen Rider Hibiki
- Kamen Rider Kabuto (Rider Form)
- Kamen Rider Den-O (Sword Form)
- Kamen Rider Kiva (Kiva Form)
- Change announcement: KAMEN RIDE
A belt based around the Rider Cards. By inserting a card into the Dark Decadriver Dark Decade can invoke the cards' abilities. In Complete Form, the Dark Decadriver is moved to the right side of his belt.
Like Decade, Dark Decade has card-based weaponry and powers: the Rider Cards. Unlike Decade, he doesn't have Final Form Ride Cards.
Kamen Ride Cards
The Kamen Ride Cards supposedly possess all the powers of the 9 previous Heisei Kamen Riders.
- Kuuga: Dark Decade uses the card to assume Kuuga's Mighty Form.
- Agito: Dark Decade uses this card to assume the form of Agito's Ground Form.
- Ryuki: Dark Decade uses the card to assume the form of Ryuki.
- Faiz: Dark Decade uses the card to assume the form of Faiz.
- Blade: Dark Decade uses the card to assume the form of Blade Ace form.
- Hibiki: Dark Decade uses the card to assume the form of Hibiki.
- Kabuto: Dark Decade uses the card to assume the form of Kabuto's Rider Form.
- Den-O: Dark Decade uses this card to assume the form of Den-O's Sword Form.
- Kiva: Dark Decade uses the card to assume Kiva's Kiva Form.
- Dark Decade Complete: A Final Kamen Ride Card that transforms Dark Decade into Complete Form.
Attack Ride Cards
The Attack Ride Cards allow Dark Decade to perform any of his own attacks, or a signature attack of whatever Kamen Rider he has transformed into.
- Blast: Grants the Ride Booker's Gun Mode rapid fire capabilities.
- Slash: Increases the damage done by the Ride Booker's Sword Mode.
Final Attack Ride Cards
The Final Attack Ride Cards (ファイナルアタックライドカード Fainaru Atakku Raido Kādo?) are Dark Decade's most powerful attacks, used for finishing off enemies.
- Dark Decade: Dark Decade performs Dark Decade Unlimited (ダークディケイドアンリミテッド Dāku Dikeido Unrimiteddo?), Dark Decade Complete Form's Rider Kick, in which Dark Decade locks the opponent in a dimension that depicts the nine original worlds and then the ten Heisei Rider symbols as Dark Decade hits the target with the Rider Kick.
- The Final Kamen Terminal K-Touch is a special touchscreen cell phone designed to attach onto the Dark Decadriver replacing the card slot, which is moved to his right hip, allowing Dark Decade to transform into Complete Form.
- Although Dark Decade never appeared in human form, he's voiced by Masahiro Inoue, just like Decade. The narration before his battle suggest that he's an alternate dimensional version of Tsukasa, most likely from the World of Negatives or an A.R. World similar to that one.