Senior Full-Stack / Backend + Unity Engineer for EdTech Curriculum, Localization

About STEMinnoKey STEMinnoKey is an EdTech platform for mathematics and STEM learning. Website: https://steminnokey.com/ Our learning application is built with Unity/C# and includes Virtual Manipulatives, MCQs, interactive games, and curriculum-based learning activities. We are looking for an experienced engineer who can work across our Unity application, backend, database, APIs, and GitLab codebase. This project begins with a curriculum and multilingual architecture upgrade. If the initial work is successful, we are looking for a long-term engineer to maintain and expand both our website and application. Important Before Applying Please visit https://steminnokey.com/ and test the application before applying. In your proposal, briefly tell us what you reviewed or tested. We prefer applicants who understand the actual product rather than submitting a generic proposal. Current Curriculum Structure Our Global Core Curriculum covers: Kindergarten 1 Kindergarten 2 Grade 1–5 Each grade has approximately 25 chapters. A chapter currently contains: 1 Virtual Manipulative 2 MCQs 2 Games The educational activities already exist in Unity. Main Development Goal Our current system may duplicate units when creating additional curricula. We want to change this to a reusable architecture: Shared Content → Stable IDs → Chapter References → Curriculum Mapping → Country Overrides → Localization 1. Chapter-Based Reusable Curriculum New curricula should be created primarily by selecting and arranging chapters, rather than copying their underlying Unity content. The same chapter/content should be reusable by multiple curricula through stable references or IDs. 2. Global Core + Country-Specific Replacement The Global Core Curriculum should serve as the base. Most chapters should be shared across countries. Only chapters that genuinely differ—such as currency, measurement units, or specific national requirements—should be replaceable with country-specific chapters. We do not want to duplicate an entire curriculum when only a few chapters are different. 3. Multilingual Architecture The underlying educational content, answers, media, and Unity interaction logic should remain shared. Language-specific text should be managed separately, including: Questions Instructions Labels Feedback Other learner-facing text We are preparing multilingual content in Excel files, including revised English and translated languages. The system should allow the English currently used in the app to be replaced with the approved English from these files and allow other language versions to be loaded from the same content structure. The architecture should also be ready for future AI-assisted automatic translation. Additional Unity Localization Requirements Some Virtual Manipulatives contain text created with the Unity “T” text tool. These texts should also change according to the selected language wherever technically practical, so that the question language and relevant Manipulative text remain consistent. We also need to improve the question display: The full question must always be visible. Short questions should be centered. Longer questions may use up to two lines. Font size may be reduced slightly when needed. The question box may be adjusted to support two lines with compact spacing. These are relatively small UI changes, but they are related to the multilingual implementation and should be handled during the initial work if practical. Existing System and Migration Before changing the architecture, you must review the existing: Unity/C# project Backend and database APIs Existing curriculum and IDs Excel/import structure Localization implementation GitLab repository We prefer incremental migration and reuse of existing working systems, not unnecessary rewriting. Backward compatibility and safe rollback should be considered. Required Experience Strong experience with several of the following is required: Unity / C# Backend and API development Database and data modeling Full-stack development Reusable/reference-based content architecture Localization / i18n JSON and Excel/CSV data integration Data migration Git / GitLab Existing production codebases Experience with EdTech, LMS/CMS, multilingual platforms, or Unity/backend integration is highly preferred. Initial Milestones Milestone 1 – USD 100: Prototype Review the current system and create a working prototype demonstrating: Chapter-based curriculum composition Content reuse without duplication Stable references/IDs Global Core + country chapter replacement Multilingual data structure Connection concept with existing Unity content Milestone 2 – USD 100: GitLab Integration After approval of the prototype: Integrate the solution into our existing GitLab codebase Connect actual STEMinnoKey curriculum and Unity content Apply multilingual test data Test it in the actual development environment Fix implementation issues Provide documented source code The second milestone must result in a practically usable implementation, not only a demonstration. Long-Term Opportunity After successful completion of these milestones, we intend to continue with a long-term contract. Future work may include: Additional national curricula Automatic translation Unity application maintenance and expansion Backend/API/database development Website maintenance and new functions Admin systems UI improvements International platform expansion We are looking for someone who can gradually understand the whole STEMinnoKey system and become a reliable long-term technical contributor. Please Answer These Questions When Applying What part of STEMinnoKey did you test? How would you allow multiple curricula to share the same Unity content without duplication? How would you implement Global Core chapters with selected country-specific replacements? How would you separate shared Unity content from multilingual text? Have you previously integrated Unity with backend/database-driven content systems? Are you comfortable working in an existing GitLab codebase and potentially continuing with us long term? Please include relevant examples of previous work.