Today's release for the Analogue Pocket and MiSTerFPGA platforms is the next entry on the DECO-16 platform. Dark Seal, known in North America as Gate of Doom, is a quarter-view action-RPG built on Data East's 16-bit custom hardware.
Kuhga / Vapor Trail (1989)Crude Buster / Two Crude (1990)Dark Seal / Gate of Doom (1990)The Cliffhanger: Edward Randy (1990)Super Burger Time (1990)Death Brade / Mutant Fighter (1991)Tatakae Genshijin: Joe & Mac / Caveman Ninja (1991)Robocop 2 (1991)Thunder Zone / Desert Assault (1991)Wolf Fang: Kuhga 2001 / Rohga (1991)Tumble Pop (1991)Dark Seal II / Wizard Fire (1992)Funky Jet (1992)Gun Ball / Nitro Ball (1992)Diet Go Go (1992)The Great Ragtime Show / Boogie Wings (1992)
Dark Seal landed as the third entry on Data East's DECO-16 platform and was the company's biggest arcade success of the year, topping Game Machine's chart of the highest-grossing table arcade units in Japan in July 1990.
This post covers a technical overview of Dark Seal on DECO-16, the work the board required, and the game itself.
Licensing:
Dark Seal is distributed through the Coin-Op Collection licensing portal, which serves both MiSTerFPGA and Pocket from the same dashboard.
Pocket patrons need to register their device and generate a key before launching the core. Step-by-step instructions and the FAQ are available on the Help page. More information can be found by clicking here and here.
Overview:
Dark Seal runs on Data East's DECO-16 hardware (PCB DE-0332-2), driven by a Motorola MC68000 (DECO Custom 59) at 12 MHz. The sound system is the standard DECO-16 audio stack, a HuC6280 (DECO Custom 45) at 8.055 MHz driving a YM2203, a YM2151, and two OKI M6295 samplers, with mono audio output.
The video system outputs 256x240 at 58.239 Hz in a horizontal orientation. Graphics are rendered by a pair of DECO 55 tilemap generators driving four playfields between them, with one chip carrying both an 8x8 character layer and a 16x16 scrolling tilemap, alongside a DECO 52 sprite engine. Layer priority is fixed in hardware rather than driven by a software register. The board carries no dedicated protection chip on the I/O bus.
Development Challenges:
The DECO 55 supports a larger tilemap layout that lets a single tile chip cover twice the vertical area of the standard layout. Dark Seal is the first DECO-16 game to enable it, and during development I was able to determine that both DECO 55 tilemap generators on the board are actually wired for the larger 64x64 playfield.
The existing emulation configurations in MAME and FBNeo only use the foreground DECO 55 in the 64x64 layout while leaving the background DECO 55 configured for the standard 64x32 layout, but the underlying hardware drives the 64x64 arrangement on both, and the core mirrors that.
Dark Seal is also the simplest I/O path on the platform. Unlike Edward Randy and Boogie Wings, which route their controls and dip switches through dedicated DECO protection devices, and Crude Buster, which routes them through a registered PAL, Dark Seal wires its inputs straight to the MC68000 bus through plain memory-mapped ports. There is no protection device and no decryption layer in the I/O path.
Core Options:
The MiSTer core includes video settings for aspect ratio, vertical scaling and cropping, scandoubler effects, and H/V positioning and sync adjustments.
Audio settings provide separate OPN FM, OPN PSG, OPM, and two M6295 PCM toggles, each with its own volume control, covering the full sound section. Arcade dip switches are directly accessible from the OSD. Game settings include per-player auto-fire with adjustable rates, mapping options for Player 1 and Player 2, and a synced mapping mode that mirrors Player 1's layout to Player 2.
Cheats are accessible from the OSD. Stage select is new for this release and was written specifically for the core rather than carried over from an existing database. It places the player on any of the game's five stages, with Default starting on Stage 1, and then releases control after roughly a minute so normal stage progression still advances from the chosen point. The remaining cheats include a Kill Dragon trigger that defeats the current boss in a single hit, per-player infinite lives, infinite energy, infinite magic, and invincibility, per-player infinite gloves and infinite boots, and a per-player Fill Magic trigger.
The Pocket core provides auto-fire with per-button targeting and adjustable rates. Its cheat set is stage select, infinite lives, infinite energy, infinite magic, and invincibility. Arcade dip switches available on Pocket are Lives, Difficulty, Continuation Mode, and Demo Sounds.
History, Gameplay, and Regional Information:
Dark Seal was developed and published by Data East, reaching Japanese arcades on June 28, 1990 and North America in July under the title Gate of Doom. It was led by Yoshiyuki Urushibara as game master, with Naomi Susa heading the programming and a soundtrack from Data East's in-house sound team Gamadelic, scored by Hiroaki Yoshida, Tatsuya Kiuchi, and Kenji Mori. Kiuchi had already scored a run of the company's boards leading into this one, and Susa would go on to direct Boogie Wings two years later on the same DECO-16 platform.
The gameplay is a quarter-view action-RPG for one or two players at once, set in the Kingdom of Etrulia, where four heroes set out to recover the God's Jade and the Sacred Crown and seal the gate before the demon Lucifer is revived. Players pick from Carl F. Graystone, a knight with a wide-arc morning star, Freya Edirne, a wizard whose attack lays down a creeping flame pillar, Riger Hawk, a bard who hurls an Elastic Spetum spear that throws shadow copies and stays immune to poison, and Kirikaze, a fast ninja who throws shurikens. An 8-way joystick handles movement and the two buttons cover attack and magic.
The magic system is the standout twist. Killing enemies fills a meter, and the spellbook HUD cycles through a rotating list of spells, casting whichever one is showing the moment the player presses the magic button. The list runs from flame balls and tornados to a Medusa head that petrifies enemies and a set of transformations that turn the attackers into harmless rats, boulders, treasure chests, or pigs. One press empties the meter regardless of what came out. The five stages run from a Dungeon of Despair through a Misty Mountain, a Floating Labyrinth, and the Delos Volcano before ending at the Gate of Doom itself, with named bosses at each, a recurring red dragon at the volcano, and the Dark Knight as the final encounter.
Dark Seal landed hard in Japan. Game Machine ranked it the highest-grossing table arcade cabinet in the country in its July 15, 1990 issue, and it placed across multiple categories of the 1990 Gamest Awards, taking tenth for Best Action, tenth for Best Graphics, and eighth for Best VGM. Reception in the West was lighter on volume but positive where it surfaced, with Leisure Line scoring it ten out of ten. The game has held a fond reputation in Japanese retro coverage ever since, often discussed alongside Capcom's later The King of Dragons and Dungeons & Dragons: Tower of Doom as one of the early arcade attempts at a co-op action-RPG.
The only regional difference between Dark Seal and Gate of Doom is the title screen and logo art. The Japanese version already ships with most of its in-game text in English other than the introduction in attract mode, and there are no soundtrack, character, or stage changes between the two releases.
A direct sequel followed in 1992 on the same DECO-16 platform, released in Japan as Dark Seal II and overseas as Wizard Fire, with the dropping of the numeral in the Western title intentionally obscuring the link for new players.
Updates:
Dark Seal kicks off the run of completed DECO-16 titles teased with Boogie Wings. Diet Go Go, RoboCop 2, Super Burger Time, Wolf Fang, Funky Jet, and Caveman Ninja will follow over the next few weeks.
The tilemap and sprite work the platform has built up over the prior releases applies to each of them directly, with the per-board differences confined to the protection paths and the audio mixes.
Today's rollup includes several improvements to all other releases. Please replace your MRA files and cores for all of DECO16.
Disclaimer: All product names, trademarks, and registered trademarks mentioned are the property of their respective owners. "Analogue", "Analogue Pocket", "MiSTer", "MiSTerFPGA", "OpenFPGA", "Data East", "NEC", "Hudson Soft", "Motorola", "Yamaha", "OKI", "Capcom", "MAME", "FBNeo", and all derivative works are trademarks, registered trademarks, or copyrighted materials of their respective holders. Use of these names does not imply endorsement or association with this post. All rights reserved to their respective owners. This post is for educational and research purposes only.