(Creating a charge up synth patch for a fantasy weapon inside Serum, working to a clip taken from the game Doom.)
The first aspect to approach when starting this style of patch is the length of the sound.
In this example, Caryle measures the length of the on-screen charge up and sets envelope 2, to that length in Serum. Use envelope 2, rather than 1, as one automatically maps to the amplitude of both oscillators.
Think about what the patch would sound like. For a charging up sound, it would increase in pitch as the charge builds. To accomplish this, you can modulate the pitch of the first oscillator with envelope 2 — this can be tuned using the matrix panel in Serum.
Because we're designing a weapon sound for a video game that will have music playing underneath, the sounds mustn't clash with one another. One way of accomplishing this is to design sounds that are not tonal.
We can do this by using unison, which creates multiple voices of the oscillator. Detuning the oscillator can help to stay away from the fundamental frequency. Both effects add harmonic interest and stereo width.
Video games usually have run time reverb and delay, mapped to the on-screen environment. Often you may want to use additional time-based effects in the design stage to further the complexity of a sound.
You need to understand the object you're designing sound for. In the case of a weapon, the player may be able to hold a charge up indefinitely. A sound needs to fit every option the player has access too.
Remember to save your synth patches at each stage for later use. Tiny adjustments on a patch can result in large sonic changes, and it's easy to forget what we've changed. Saving many versions allows you to access the previous versions of the sound. These could also come in handy to test all the different sonic options for each element, which will help you fine-tune your sound design.
You can use the noise section in Serum as an incredibly simple sampler. Anything imported into the sampler will be run through all the same effects as the main patch.