With the rise of game jams and engines like Pico-8, there's been a rise in Caravan-style shmups, with some devs like Crow's Nest mostly focusing on releasing small, bite-sized scoring based shmups. Full length shmups also now regularly feature caravan modes. So I figured it's worth talking a bit about caravan shmup design because it's an extremely fun and versatile style of design.
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For those unfamiliar, "caravan shmup" refers to a style of 80's-early 90's shmups, mostly made by Hudson, which were designed for scoring contests.
The term can be used to describe all short, scoring-oriented shmups. But when I say "caravan-style" I refer to how their structure & scoring worked in Time Attack modes :
- The Time Attack modes were 2 or 5 minute long modes where you'd play a single stage, either until a timer runs out or to completion.
- Enemies would spawn in small waves. Once the enemy wave is destroyed/leaves the screen, the next wave will spawn.
- Time bonus. If you can finish the stage before the time runs out, your remainder gets converted into puntos and added to your total. A lot of games simply keep going after you beat the stage boss and let you score some extra points in the next part of the game.
It's a small set of rules that create a lot of variety & depth while potentially giving meaning to nearly every frame of gameplay by tying score & time together directly. All while preserving the abstract scoring layer for extra mechanics on top of speed. It also makes every run feel different without relying on RNG. This style can be applied to almost any genre, even turn based ones.
Here's an older STG Weekly episode talking about the history of caravan shmups if you want to learn the proper history.
Super Star Soldier (2 Minute Mode)
This game's time attack is probably the quintessential caravan mode. It has the enemy speed killing, it has non repeating enemy waves. It has a preset boss arrival point which you can't change.
As basic and by-the-numbers as this game is, it does demonstrate an important element of older caravan games - the background layer. Its full of boxes and other objects which die quickly but not immediately, and as a result compete for the player's time. The player has to figure out how to optimize box destruction while making sure to kill enemies as quick as possible. And because the way enemy spawns varies based on the player's kill speed, these routes will probably evolve over time.
The boxes and terrain serve another important function - they are landmarks players can use to have an easier time remembering enemy waves and judge how well they're doing. They can use a certain box or platform as a visual anchor point, judging their pace by how close enemies spawn to it.
Memorizing a lot of enemy waves in a black void is a pretty tedious and frustrating process, anything games can do to make this easier helps.
Star Soldier (2 Minute Mode)
This game is older than Super but in many ways it's a lot more interesting and ambitious, even if the execution is kinda crappy.
The basics are the same but the game has an extra gimmick - its weird "stealth" mechanic. Some tiles are special zones where you can't be hit by enemy bullets, but you also can't shoot. As infuriating as this idea is (not shooting is almost a failure state!), it helps give meaning to the terrain and boxes. The tiles now restrict your movement, which itself mixes nicely with the dynamic spawns - if an enemy comes in too early, it might be directly on top of a column of "stealth tiles", making it harder for you to approach.
The game has repetitive enemy waves, which might seem like a limitation and flaw but actually works out quite nicely. It lessens the amount of hard memorization required because you only have to learn a pretty short sequence, and it allows you to plan ahead more effectively. The game also has special, destructible tiles hidden in the environment - destroying them gives you points, and each extra tile gives exponentially more points. These tiles are like boost pads in racing games - they anchor your routes and keep you focused, while also creating tension between the players different goals.
Additionally, the game experiments with spawns that are affected by the player's positioning - if the player's on the left, they will spawn on the right and vice versa. This is yet another layer that makes the ostensibly simpler spawning system more dynamic than the sequel's. And that's the theme of the game - as awkward as the "stealth" implementation is, the interactivity and tension between different elements make it a lot more dynamic and fun in the long run.
It's important that caravan devs think about how the dynamic waves interact with the terrain & how it all snowballs outta control.
Radirgy & Karous
Milestone asked an important question : what would happen if you had not 1 but 2 independent caravan spawners? The games are the answer, and they are fantastic.
By having 2 spawners they took the conflicts between the box/tile destruction of the ground layer and the enemy layer, and transferred it to the enemy layer. Even the types of enemies that spawn on the 2nd caravan layer tend to be carrier ships with boxes on top! And because it's now a separate caravan spawner, the 2nd layer is also dynamic, unlike the static ground layer. By overlapping caravan spawns like this, you increase the chaos exponentially.
The games also do some other interesting stuff to link the spawns together and create conflict, such as a system where you level different weapons by using them which then feeds back into the scoring. Or point items you can bounce with your melee attacks, which create YET ANOTHER layer of dynamic objects that conflicts with the 2 caravan enemy layers. Also the ground layer is still relevant in Radirgy.
Devs should think about how to apply the dynamic, player driven concept of caravan spawns to things like levels themselves, because that leads to even more conflict, chaos and depth.
Hyper Demon
The game might be a different kind of shooter, but at heart it's still a modern caravan scoring game.
Instead of spawning enemies in waves, the game has a certain amount of total enemy slots available, which get taken up by enemy units once they spawn. What constitutes a "unit" isn't as obvious as it might seem though because a group of 3 Scuttles counts as 1 unit, and skulls exist entirely outside of the spawn system. The total number of available slots increases over the course of the stage.
This system creates an "internal" priority system where you can selectively pick off specific enemies to manipulate the spawns while keeping others alive for a bit later. Since the game has no enemy timeouts, this can even be exploited by leaving the harmless spider enemies alive.
Besides this, the game also does a really good job at having one enemy kill feed into the next in a very direct manner. You can kill an enemy, have it drop a gem, then you can immediately use that gem to insta-snipe another enemy. Or you can kill that first enemy quicker but sacrifice the gem. Or you can kill a bigger enemy/small group, charge up your ricochet attack and use it to instakill an enemy that would have otherwise taken a lot more time. Everything feeds into the next thing, every action conditions what sorta attacks you can do next.
Devs should think about how to expand the caravan spawners "internally" instead of just adding more stuff on top. And they should think more deeply about how one enemy kill feeds into the next.
Conclusion
So to sum up :
- Caravan spawns are awesome and should be used a lot more
- Devs of caravan games should make sure to soften the memorization via memorable visual elements
- Devs should think about how to make the levels tie into the dynamic enemy spawns
- Devs can plop more caravan spawners on top of each other to make things even more dynamic
- Devs can build on the caravan spawns "internally" by having different enemy kill order affect how and when new enemies spawn
- Devs can think about how to not only tie different waves together, but also how to connect individual enemy kills
- MAXIMIZE TENSION, MAXIMIZE INTERCONNECTEDNESS, WORSHIP THE MICRO NOT THE MACRO
