Inside the Mach Engine: a Dev Interview
Our engine lead on rewriting a decade-old codebase, what broke in production, and the bug that became the game's most-loved feature.
Why Rewrite a Working Engine?
'Because the old one lied to us,' M. Chen says flatly. The original engine ran beautifully on 2013 hardware — and hid a physics step that drifted with frame rate. Fast devices got subtly different gameplay than slow ones; nobody noticed until a frame-step analyzer proved it.
The rewrite took fourteen months and the team shipped three seasons of content simultaneously. 'We rebuilt the plane while flying it, which everyone warns you about — because they're right.'
Every engine is a pile of decisions that seemed smart at 2am. Ours just got documented.
What Actually Broke in Production
The honest post-mortems, because every engine has them:
- Week one: a pooling bug replayed one player's crash audio to their entire lobby
- Month two: the fixed-step solver drifted on one specific foldable — 1,400 devices affected
- The ghost system recorded inputs, not positions — a mid-race lag spike could corrupt replays
- A memory 'optimisation' that freed the launch sound one frame early — silent starts for a day
The Bug That Became the Feature
The most beloved accident: a sign error in the slingshot code that launched pilots backwards — spectacularly. Instead of just fixing it, the team kept the behaviour as a deliberate 'reverse launch' easter egg on one circuit per season.
'Players found it in a day, clip-posted it everywhere, and suddenly a bug report was a feature request.' The lesson Chen keeps repeating: ship the fix and the celebration — players forgive bugs, they don't forgive boring responses to them.
Rewrite Ledger
If You Only Remember Three Things
The rewrite happened because the old engine drifted with frame rate — fairness demanded it.
Four production incidents in year one — documented, fixed, none repeated.
The backwards-launch bug became a seasonal easter egg — hunt for it.
Related From the Journal
Common Follow-Ups
Race the Engine They Rewrote
Fourteen months of engineering hides under every launch — go feel it.