Friday, 30 December 2016

Questionable Moments in Game Design: Metal Slug and Scoring

 Don't worry. I'll talk about something that isn't a 2D platformer next time.

For arcade games designed to have endings, the Japanese approach was basically built into three distinct phases as a business plan.
  1. Release Phase. During this period players have no idea what's inside a game and are expected to run out of credits regularly, either leaving the machine free for someone else to see what's going on or pumping in extra cash to see the ending. This is the most profitable period for the game's release for arcade operators.
  2. 1cc Phase. During this period there's less immediate buzz, but players who have learned and practiced the game well enough are now beginning to beat it in a single credit. The idea is that people watching a player perform well would be drawn back into the game now that they know it's possible to get good value with. A game reaching this phase grants extra life and income for the arcade operator.
  3. Optimisation and Scoring Phase. The player base for the game has diminished, but with robust scoring systems the community is now actively competing to not just finish the game on one credit, but to do so in the absolutely highest scoring way possible. There's less cabinets operating the game, but the arcades that have become hubs gain excellent value on the board they purchased.
The Metal Slug series' sound design, animations rife with personality, visceral impacts and good-to-brilliant level design covered those first two phases excellently. However, the scoring phase ultimately proved to be somewhat degenerate. I have seen more players compete for third-party measured speedrun times instead of using the game's internal measures for success. There's some great ideas in the series, but the precedent Metal Slug 3 set for excess resulted in both Mega Enterprise and SNK Playmore not only bolting on more and more bad ideas, but throwing out some that had actually worked in the first place.

As such, today I'd like to go over what works about the series' score systems, what doesn't and what alterations I'd make for a potential ninth (including Advance) title in order to make it a more satisfying experience in years to come.

Starting with what does work, let's talk about the end-of-mission bonuses. There's two main ones here: the vehicle bonus and the prisoner bonus.

The vehicle one is the most straight-forward: if you're inside a vehicle upon defeating the mission's boss, you receive extra points. This means a player is rewarded for acquiring a vehicle and keeping it intact through to the end even with the extra large hurtbox. The prisoner bonus works very similarly. Every time a prisoner is rescued, an icon appears at the bottom of the screen. At the end of the level, each of these symbols is worth a set amount of points. Similar to how the vehicle bonus is lost upon the vehicle's destruction, so too is the prisoner bonus lost if the player dies at all during the level. In the first game, a 2-player session would also give an extra GREAT! bonus to whoever found the most prisoners. That was easy to game and later altered in sequels to a no-death bonus. That's fine and dandy, but the player is already rewarded for playing the base game of mowing through foes and not getting hit  thus I think it's a redundant feature.

The second way to gain points is through picking up items. Sometimes prisoners drop them, sometimes they're just part of the level. Some more are hidden in secret locations that need to be shot. Those lend a sense of discovery and mystery, which is useful when thinking of ways to extend an arcade game's life. Most importantly though are the items like this frog sitting here.

That frog is worth 50 000 points! However, there's an enemy below it that will destroy the bridge if you don't reach it quick enough. In an run 'n gun platform game, I love having risk/reward situations like this one. Get a big boost if you're good at movement, die a costly death if you aren't.

That's where the stuff that clearly works ends, however. Now we need to talk about the points for dealing damage to enemies. At first, it seems pretty straightforward: 100 points per projectile hit, 500 points for each melee attack.
I grew up with the white blood toggled.

At its core this is a good idea, as it makes melee attacks an objectively better option for scoring at the cost of being much higher risk given the necessary proximity to enemies. However, there's other factors at play here that result in degenerate play.

The problem with this is that the Metal Slug games don't just provide a knife and gun. They also provide the player with grenades and more powerful weapons with limited ammunition. These both also score that measly 100 points per hit. In other words, the optimal scoring routes involve actively avoiding every high powered weapon in order to milk the most pistol shots from every enemy that cannot be stabbed. This might seem like a minor optimisation, but if you set a cab to a higher difficulty it can result in millions of points difference due to the extra hits required to defeat enemies. While this can be argued as a further risk/reward, it does so while removing any sort of improvisation or thought. Part of the series' appeal is the visceral satisfaction of wreaking havoc against a huge army and such scoring actively discourages such spectacle from occurring.

That's not to say the later games ignored the points-per-shot problem. Metal Slug 4 made an attempt at putting in a combo system to offset it. In 4, an item can be found that temporarily grants medals for dispatching enemies quickly. These medals then behave like prisoners, with a score at the end of the mission if the player hasn't died before then. Tying together item collection and prisoners sounds like something that would provide immense depth, but in reality it barely adds some breadth. Since the combo system is tied to items, any engagement with an enemy outside of this period is completely irrelevant. Thus, it's best to spend the minimum required resources to rack up the medals then return to farming with the pistol the rest of the time.

When SNK Playmore reformed and reacquired the series' rights, a different system was developed for 6 and 7/XX. Now, high powered bursts of damage rack up a combo gauge that when filled causes any defeated enemy to release a pile of coins! The idea was to encourage burst uses of resources (made all the easier with the ability to hold and switch on/off two weapons), but tying the system to a set number of hits and exploding enemies has two big problems. The first is that the player has very little control over the timing of these combos. They often just happen when a lot of foes are on the screen at once. Compare this to something like the recently released Blue Revolver where a player chooses when to cash in their combo bonus based on special weapon usage. Metal Slug games also have fairly limited movement. This makes chasing down coins far more difficult than it should be and kills their own bonuses for being collected in quick succession. Putting this in the thick of the fight also makes things much more frustrating than a game like Fantasy Zone, which did the coin collection gimmick after boss fights. Speaking of bosses,  the reliance on enemy deaths also makes this system completely irrelevant in the face of boss battles. Thus, the bosses are still encouraging the player to farm with the pistol.

Another problem with the scoring rules is a matter of level design. From Metal Slug 3 onwards, the titular metal slug's appearances became increasingly sparse. It could be somewhat forgiven in that game given SNK was about to go bankrupt and the focus was on a spectacular last hurrah, but it set a poor precedent the rest of the series followed. In 3, the first and final missions are the only two where the player can bring a vehicle all the way through, the latter via heavy abuse of invulnerability frames. By 7/XX the player can go through the entire first mission without even finding a vehicle! Compare this to the meticulous design of the first game's missions. Missions 1 through 3 present the vehicle as a thrilling powerup halfway through. 4 then places one right at the beginning and tests a player's situational awareness in order to receive it.
How do you reach it? It's dangling right there!
It still gives another later so a player isn't left feeling like they made a suboptimal call. Mission five provides two slugs for free to warn the player of the heavy onslaught to come and then the final mission forces the player to throw themselves into the heaviest part of a fray if they want that extra power. These missions tie the end-of-mission scoring bonus to situational awareness while also giving a thematic powerup. Later games ignoring this aspect hurts the theming as much as it underutilises a scoring element.

6 and 7/XX throw a whole new problem in the mix as well: character abilities. The aim was to accentuate various elements of the game according to individuals' playstyles but in practice there's pretty much two objectively superior options: Ralf and Clark. When playing for survival, Ralf takes two hits instead of one to lose a life. He can also punch tanks, netting around 10,000 points from enemies that usually give around 2000 with the pistol. This would be the most blatantly best option in the game, except that Clark's scoring potential is even better! Upon performing his Argentinian Backbreaker, he gains 1000 points. Doubling the knife bonus is one thing, but if he hits another stabbable enemy within a second or so, that score doubles to 2000. A third? 4000. On it goes until Clark is suddenly hitting 32000 points for what would normally be worth 500. Did I mention he's invulnerable while doing this, reducing any sort of risk in the risk/reward game? On the flipside, Marco's ability is increased pistol damage, making him the most blatantly terrible choice for scoring as it reduces how much he can farm extra points.

The end result of all these issues is that players have moved into speedrunning the games. This results in heavier use of resources to burn through opponents as fast as possible, but it saddens me to see the game's internal scoring be perceived as irrelevant. Given the game's relatively simple movement, I also think that a focus on pure speed is less thrilling than it is in other games and doesn't do the job of creating that late-game depth to keep people around. I played a great deal of the series in my youth but have drifted away from it precisely because I had little motivation to learn more than pragmatic 1cc routes.

SNK Playmore has rebranded itself in the last few months back to SNK and is moving away from pachinko machines back to computer game development. As a result of this, I think it's inevitable that we'll be seeing a Metal Slug 8 (later revised as Metal Slug Xrd) soon. Given my complaints about the series so far, here are some adjustments I would like to see made in order to make a more fulfilling experience for top end players:
 - More valuable item pickups in precarious locations. Remember that frog near the top? Or how about this gem?
I'd like to see more focus on risky item placements with large payoffs. Some can be hidden so players spend some time exploring every nook and cranny while learning the game. Metal Slug's never been afraid of having some tense pure platforming and these items are a great way to demand perfectionism beyond jumping gaps.
 - Make the Metal Slug the most exciting thing in the game.
The Metal Slug is so damn cool that the games are named after it. Acquiring the tank should be exciting, and keeping it alive through a whole level should be the best thing for scoring purposes and player satisfaction due to its large hitbox. Every level should have the ability to reach its end with the Slug intact. Provide a melee scoring bonus like the knife, and consider allowing it to destroy tanks by jumping on them (a very risky option when several are unloading their ordinance). If an obstacle needs to be destroyed but can't be jumped on, make the points given by destroying it with the slug's vulcan higher than if it had been shot at with the pistol. Given how gimmicky the games have become since 3, make the Metal Slug extra special by returning to it as the sole vehicle for a game.
 - Remove character abilities, or make them a dipswitch toggle.
I liked the weapon management in 6 and 7, but the spread of character abilities made some characters a clear choice. Characters like Fio are fan favourites and players are going to wind up disappointed if they're never allowed to use them in high level play. Either make abilities an option with its own high score board or remove them entirely. That way, if further advertising of other SNK properties like the mobile phone game did is utilised, every player gets their preferred aesthetic choice.
 - Remove the combo system and replace it with this.
There are situations in 4, 6 and 7 where you can gain no extra scoring from an encounter with, say a sole tank. None of the previous systems added extra levels of mastery when fighting bosses. Speedrunners on the other hand, used resource management and various tricks to get quick kills that make use of the game's visceral weaponry.
Let's tie these all together like so:
For every enemy that cannot be stabbed, put an internal timer on it. Give an extra point bonus based on how quickly it was destroyed. This can be a concrete number appearing, a flash on the total score, or in my preferred case, an extra explosion that's larger the quicker the defeat was. Leave the traditional explosion animations as the base result, with quicker kills being even flashier. Players should still feel exciting about defeating an enemy while getting even more pumped when they show how deftly they handled a situation. On top of this visceral satisfaction, the player now needs to work out when it's best to burn through a weapon or grenade. Is this tank worth spending a grenade on, or will I get a greater point bonus for saving it on another enemy type or the mission's boss? Am I confident that I can get through the next wave of enemies without assistance, or should I use some grenades for safety?

With these changes I think a new Metal Slug game could have much greater longevity as a scoring game while still maintaining the visual spectacle that helps the series to stand out ahead of games such as Contra.

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