Here are some free and easy-to-use tools for constructing non-realistic sound effects in games. For now, this is mainly about DrPetter’s sfxr and some forks of the program.
sfxr by DrPetter is a free and open-source tool for generating simple video game sound effects. Designed for game jams, it provides a lot of quick and accessible features for building wave file samples from primitive waveforms. There are seven pre-defined template generators (pickup, shoot, explosion, etc), one purely random generator, one mutator option, and several sliders to control specific parameters of the sound effect.
sfxr is used most often in smaller indie and retro games, and quick usage of the template generators is often easy to spot. That said, you can use sfxr to produce basic WAV samples, then refine them in other editors like Audacity or tracker programs.
sfxr Fork with CLI support
todo – investigate this fork with CLI batch export support.
Chiptone is a browser-based, WIP sound effect editor by SFB games. Like Bfxr, it expands significantly on the kinds of sounds that can be produced. The interface is more fleshed out and less spartan than that of the *xfr’s.
usfxr for Unity
usfxr by zeh is a fork for Unity that can play back sound effects on-demand, without requiring exporting to WAV. I haven’t gotten into the Unity ecosystem, but being able to make subtle differences in SFX without needing to export all variations of the sound as WAV files is pretty appealing.
edit 30/Aug/2016 – added Chiptone