Quick answer: Yes, in some form, because updates break things that worked. You don't need a huge automated suite, but you do need a way to catch regressions: a critical-path checklist before releases plus per-version monitoring to catch what slips through.
Regression testing means checking that new changes haven't broken things that previously worked. Do you need it? Yes, in some form, because regressions are inevitable whenever you change code. But "regression testing" can be lightweight, it doesn't have to mean an elaborate automated suite you don't have time to build.
Regressions Are Inevitable
Whenever you fix or add something, you risk breaking something else, that's a regression, and it's a normal, unavoidable consequence of changing code. A game that ships updates will introduce regressions; the only question is whether you catch them before players do. That's what regression testing is for.
Bugnet tags issues by version, so a regression shows up as a new problem on the latest build. But catching them earlier, before release, is better, which is where some form of regression testing earns its place.
It Can Be Lightweight
Regression testing doesn't require a massive automated test suite. For most indie games, a focused checklist works: before each release, verify the critical paths (launch, save/load, core loop) and the areas you changed still work. This catches the most damaging regressions without an engineering investment you can't afford.
Bugnet's history of past issues shows which areas tend to regress, so your checklist targets real risk. A short, focused regression checklist is far more achievable than full automation and catches most of what matters.
Pair Pre-Release Checks With Monitoring
No regression testing catches everything, so back it with per-version monitoring. Your pre-release checklist catches the obvious regressions; monitoring catches the ones that slip through, flagging a new version that's crashing more than the last. Together they cover far more than either alone.
Bugnet's per-version crash tracking is the monitoring half, surfacing regressions fast after release. So yes, you need regression testing in some form, a lightweight critical-path checklist before releases, paired with per-version monitoring to catch what slips through, which gives you regression coverage without building a test suite you don't have time for.
Yes, in some form, regressions are inevitable when you update. But it can be lightweight: a critical-path checklist before releases plus per-version monitoring to catch the rest.