Website Game Top-Up Integration

I’m creating an online top-up portal where gamers can purchase credits or items for their favorite titles directly from a website. Users will access the service exclusively through this website, so the entire flow—from product selection to payment confirmation—must be browser-based and mobile-responsive.

Here’s what I need:
• A clean, modern front-end that lists supported games and their available top-up options.
• Secure payment integration (e-wallets, credit cards, and preferably PayPal or Stripe).
• Real-time or near-real-time API calls to each game publisher so orders post automatically once payment clears.
• An admin dashboard to add/edit game SKUs, adjust prices, view orders, and export reports.
• Basic user account system for order history and receipts.
• Solid security practices: HTTPS, input validation, and protection against common exploits.

I’m open on which games, currencies, or items we start with; your experience and suggestions are welcome. Code should be well-documented and easy to maintain so I can grow the catalog later or, if needed, branch into a mobile app.

Please let me know your preferred tech stack, estimated timeline, and any similar work you’ve completed.