While TJAPlayer3 is the most widely used simulator in recent years, other simulators have came before it and others will succeed it.
Not much information will be documented on these simulators unless someone volunteers
Taiko-san Jiro (太鼓さん次郎) otherwise known as Taikojiro, is the first taiko simulator.
Taiko-san Daijiro 2
Taiko-san Daijiro 2 (太鼓さん大次郎2) is a Taikojiro style simulator made for mobile devices.
App Store (iOS)
Google Play Store (Android)
Taiko-san Nantoka (太鼓さんなんとか) is a higher quality, smoother version of Taiko-san Jiro, which aims to look like the 2nd gen arcade version Taiko no Tatsujin 14.
Taiko Unity is a discontinued simulator built in Unity. Distribution is currently UP. Taiko Unity features fully customized 3d Don-chan and very nice graphics. However, it is prone to audio lag, and you can't play custom dans or mp3 files.
Taiko Web is an open-source, web based simulator developed by Bui. It supports both custom TJAs, .osu files, 2P online, and a host of other features, localized entirely within your browser.
Official Taiko Web: https://taiko.bui.pm