Anyone old enough to own a Sega Saturn should know the name Radiant Silvergun quite well. Originally released to Japanese arcades and then ported to the Saturn in Japan, Radiant Silvergun is to shoot-'em-up (shmup) fans as Dracula-X: Rondo of Blood is to Castlevania fans. It's a game that has long been considered a holy grail, with near-mint copies often fetching more than $150 on the used market. Now, thanks to the magic of digital downloads, you can lop a zero off that price and play to your heart's content.

If Radiant Silvergun means nothing to you, here's a quick history lesson. Released in 1998, Radiant Silvergun broke the mold for the genre. The game starts you off with access to all seven weapons, includes multi-part bosses that must be defeated in the correct manner and features a color-coded combo chain system. It took Japanese arcades by storm, and the Saturn version of the game was popular among import gamers both in North America and Europe. This was long before importing a game was as easy as clicking on a Web site.

The color-coded chain combo system is the element of Radiant Silvergun that stood out the most when it was compared to other games of its day. Although Treasure had experimented with color coding in Silhouette Mirage and would later go on to make it a core feature of Radiant Silvergun's spiritual successor, Ikaruga, this was the first time such a feature was a major component in a shmup.

Chain combos are an important element in Radiant Silvergun because they allow you to level your weapons faster. As your weapons level up, they become stronger. This is a minor help during the main stages, but it is invaluable during boss fights. In order to maximize your score during a boss fight, you must take apart the boss piece by piece. Just shooting for the center will cause the boss to self-destruct, giving you no credit for the kill.

In a nod to its fans, Treasure included a brand-new Ikaruga mode in the XBLA version of Radiant Silvergun, and it uses an Ikaruga-style chain combo system. To unlock this feature, you must have at least one Ikaruga Achievement on your profile.

Level design is Radiant Silvergun's strong point, with each one serving as both a puzzle and a harrowing test of reaction time. When you first start playing, it's likely that you'll use the vulcan gun as your primary weapon. This works, but it isn't always the best choice. The developers gave you seven weapons, and they expect you to use them. As a result, each section of a given level is designed with a specific weapon in mind. Learn what works best in each situation, and the game reveals a surprising amount of strategic decision making.

Visually, Radiant Silvergun holds its own, thanks to the fact that the visuals have all been rebuilt from scratch for HD. Fret not, purists: The artists who worked on the visual overhaul were careful to retain the original look and feel of the game. This is still recognizably Radiant Silvergun, complete with its somewhat-dated, low-polygon look; it's just that all of the sprites are clean and sharp. You can switch to the original art assets, but there's really no reason to do so.

Both arcade mode and the previously Saturn-exclusive story mode are present in the XBLA version of the game. The anime cut scenes from the Saturn version have been remastered and look very nice in HD. They are even subtitled in English, but don't expect that to make the story any easier to understand. It is uniquely Japanese, featuring a stone that destroys Earth so a time-traveling robot can go back in time, clone two people and start the human race anew. Just nod and go with it. You don't need to understand a lick of the story to appreciate the depth of the gameplay.

Additional game modes include co-op play (both local and via Xbox Live) as well as a score attack mode that allows you to post your scores and replays to the leaderboards. Score attack mode doesn't allow for customization in order to ensure a level playing field — and by level playing field, we mean hard. Make no mistake about it; Radiant Silvergun is an incredibly difficult game by design.

You can adjust your lives and difficulty in the normal modes, but score attack is all about pure skill. Much like Ikaruga, Radiant Silvergun is a game that can be finished in a single sitting, but there are a limited number of people who can actually do so. Most mere mortals will need to use a few continues (and expletives) along the way. If you need help making it through a level, you can always download a replay file from one of the top scorers on the leaderboard.

It may not have the visual flash of current-generation games, but Radiant Silvergun still shines just as brightly today as it did 13 years ago. Unless you absolutely despise the genre, Radiant Silvergun is a game that needs to be in your collection. It's just as much a landmark in game design as it is a joy to play.

Score: 9.0/10