Kill the deadline i.e. Push the date you don't want to end up in the situation that the CD Projekt Red was in with CyberPunk 2077 If pushing the deadline let's you deliver an smooth experience for the players it's your best shot at success otherwise a buggy game won't only ruin the projects reputation but also studios as well and as they say "first impression is the last impression" if the game has several issues at launch it will lose its player base and no one would want to return to it even if you fix the issues later

As with any project it should all start with your team, give them the best chance of delivering successfully first time. Minimize rework by dedicating time to understanding the work before it's begun. Make sure your workflow pipelines work for your team. Test throughout your project, Story Acceptance Testing can gain back valuable time at the backend during the finishing phase.

The deadlines are always seems tight, but for those who never follow the project plan and do the homework. before start design and development must understand the game storyboard 100%, do business analysis, prepare the proper game design document and project plan with ensuring nothing is missed. Split the tasks in modules and chunks as per the game storyboard stages , check the dependencies and set the priority of the tasks either frontend game assets or backend game engine development etc. So take a milestone start development priority wise, and align the dependencies for the next milestones. The strategic development always help you to overcome the performance issues with the clean development environment. keep testing millstones:)

From the outsource point of view, when a client comes with tight deadlines, make sure to assign seniors to such a project. They've had their fair share of fails so can adapt and perform in the best way for you and your client.