This week saw the introduction of mine-laying enemies:

The mine frequency/density has been dialed up in that clip just for testing purposes – it’s a bit too much to handle with a base/un-upgraded ship.

Aside, $0.02, fwiw: I believe that features should only be added to a game when there’s a rational justification for them. For example, not every app needs a match-3 mini-game in it “just because you can”. Raw feature-count alone shouldn’t drive development – everything should serve a purpose, otherwise it’s likely to end up being just a cobbled together collection of random ideas, rather than a cohesive whole.

The mines will serve two purposes:
1) to provide additional variety in the early game
2) to provide additional difficulty in the later game

Mines are essentially the opposite of bullets. Bullets come at you fast, but they’re relatively small and easy to dodge. Mines come at you slowly, but are larger, harder to dodge. Mines tend to fill up the screen in a more-persistent way than bullets. But since they appear at current enemy location, there may not be much time to prepare for them.

Mines are also a bit like rocks, in that they’re bigger/slower than bullets, though the rocks serve (primarily) a slightly different purpose: to discourage the player from just “camping” on the edge of the screen where it otherwise might be marginally safer. Player has plenty of time to see rocks coming from top-of-screen and decide if edge or center is a more-attractive path:

Hey, that was some fancy maneuvering, even if I do say so myself!

But back to mines, and difficulty progression…

The general way the difficulty progression works is: At the start of each wave, some overall decisions are made regarding the type, character and quantity of enemies that will spawn. Wave content isn’t predefined, but it isn’t purely random either. Essentially, the farther along you get, the harder the wave will be.

Wow, what a novel and unique idea!!! (IOW: duh, why would I even bother writing that?)

Early on, mine-laying enemies will occur every few waves, but it’ll be an all-or-nothing decision. That is, bullet-shooting enemies won’t also occur with mine-laying enemies in the early waves. The combination of the two simultaneously seems too challenging for the early waves. But at least you’ll have seen the mines in small numbers before you’re spammed with them later.

Later on, both types of enemies will be allowed to occur simultaneously. Beyond some “threshold” wave (which has yet to be properly determined through playtesting) a spawned enemy might be either a bullet-shooting or mine-laying variant. This has the effect of filling the screen with both fast- and slow-moving projectiles (in addition to the enemies themselves, which must also be avoided) which is quite a bit more difficult to find a safe path through than either one by itself.

The wave generation is essentially just a set of probability and distribution tables, then once set up it’s effectively all data-driven til the next wave. But it functions roughly like:

I don’t think that I’ll need to allow a single enemy to be both a shooter and miner simultaneously. The code is structured to easily allow it, but I’m holding off until playtesting can determine if it’s going to be needed, perhaps at some “very-late” stage of the game (for hard-core, fully upgraded players).

But it’s too early to tell yet – I’m not (yet?) good enough at my own game to playtest it that far!