The design of rhythm games is rarely discussed. Many people assume that there just isn't much too them, and that sets them apart from each other. Because of this, I've decided to write a series of somewhat analytical blog posts about rhythm game design. This is the first, where I'm looking at gauges, lifebars, and meters.
Like most things in the rhythm game world, these have many names depending on the game you play and who you're talking to. For the sake of this post, I'm calling them gauges overall and some specific types have other names. First I'm going to talk about some common types and then game-specific examples.
First Step, Categorisation
Most rhythm game gauges have a few things in common. They can fill, they can drain, and they have some kind of pass or fail state. So the things that can categorise them are what the pass and fail states are, and what causes it to fill and drain.
Of course, this can cover a wide variety of potential systems, but there are two main common ones:
- Hits fill, Misses Deplete, Pass based on a Threshold
- Hits fill, Misses Deplete, Fail on depletion
These each can be given a simpler name, I like "threshold-based" and "life-based".
These are probably the most common gauge system, and can be found in games including:
- Dance Dance Revolution
- In The Groove 2/Stepmania
- DJMax (entire series)
- Pump it Up
- Superbeat XONiC
- Guitar Hero's "Rock"
- Beatmania IIDX (Course Gauge, Hard Gauge)
- Sound Voltex (Excessive Rate, Permissive Rate)
- Ouendan/osu! (This is a special case, I'l talk more about it later)
and even many others beyond those.
They are probably the simplest of the gauge systems. They start at a certain amount (usually 50% or 100%) and that falls as you miss notes, and rises as you play well. If you hit 0%, you've failed the song, and are either kicked to a results screen, or allowed to continue but graded with an F.
There are a lot of benefits to this system. It's very simple to implement, and adds tension to the game. It's also good for arcade owners - if a player fails out of a song, they're going to need another credit.
However, you should be careful when using this system, to get the fill and depletion rate well balanced for how difficult you want the gauge to feel. SDVX's Blaster Rate is a good example of doing this wrong. It drains incredibly fast, but fills very slowly. This, to me and many other players, makes it feel punishing and "unfair"
It's also worth mentioning the starting position of the gauge. DDR/ITG's start at 50%, requiring the player to play well to reach 100%. SDVX and IIDX start theirs at 100%, so from the start you have the best chance - although you can still fail fairly easily as both drain quite quickly.
This system also suffers from the fact that a chart can be made difficult to pass deliberately, by using bursts of more difficult or faster patterns to cause a player to fail. This can easily feel unfair if the rest of the chart is fairly easy going.
These are maybe the second most common gauge system, being found in games including:
- Beatmania IIDX
- Sound Voltex
- Taiko no Tatsujin
- Pop'n Music
Like with life-based systems, these increase with correctly hit notes and decrease with missed notes. The main difference is how they determine if you pass or fail.
Usually with a threshold-based bar, there is no way to fail a song in the middle of it, and if you pass or fail is determined by if you are above a certain amount of life at the end of the song.
These have a few advantages over the life-based systems from before. The player always gets the whole song and if a song has a bursty section they can always regain life after it is over, making them feel fairer. As with the other systems, you need to be careful balancing the drain and fill rates, but also setting the threshold at a reasonable point. (70% to pass is common.)
Unlike life-based gauges, these can also feel very different to each other depending on the drain and fill rate. For example, Taiko no Tatsujin's spirit meter fills very slowly, and it's common to be fairly far into a song before you are above the threshold for a pass. This is balanced by the fact it also drains fairly slowly, making it difficult to get back out of a pass once you are close to one.
Compare that with pop'n music's groove gauge, which drains quite a lot quicker. A player playing on the limit of their ability will pass in and out of the passing zone fairly frequently throughout the song.
These also have a lot of their own problems. The most common is a charting technique seen in games using these systems that is designed to increase difficulty, which I have heard called various things, notably a "BMS Ending". Basically, it is putting the most difficult section of the song right at the end, so the player is likely to fail the song unless they play it near-perfectly.
There is also a possibility for a player to feel "cheated" by the life system. This seems common in sound voltex, where it is easily possible to end a song on 68 or 69% life, while a pass is 70% or above.
Sidenote: ARS and multi-gauge systems
Sound voltex also has another gauge system called ARS (the "alternative rate system"). It allows the player to play a song on the game's "excessive rate" system (a life-based guage) but if they reach a fail, it switches back to the default system, which is threshold-based.
I didn't feel this was worth mentioning earlier as it's pretty SDVX-specific, I've never seen it used in other games.
osu!'s gauge is a fairly unique one with a LOT of issues. It appears as a normal life-based system but with the life constantly depleting instead of depleting on a miss. Initially I was confused by this system as I thought it made no sense, there was no logic for it, and as far as I can tell there basically isn't.
If you come out of a fast section of a chart into a slower section, you can fail simply because the bar will have depleted by the time you have a note to hit. It's purely frustrating and just adds to the confusing system.
So, in conclusion. The gauge a game uses can change the feel of it drastically. Having a gauge that is too strict will make it feel unfair, and sometimes charts will have to take the system into account. Different systems have upsides and downsides in terms of game feel.1
I hope this post has been at least slightly interesting. If I got everything wrong or there was something I forgot to mention, leave a comment!
also, osu! sucks.