Playing RuneScape on Nintendo DSi: Is It Possible?

No. RuneScape (Java / C++ client) requires:

• Windows / macOS / Linux (x86/x64).
• 2+ GB RAM, OpenGL 2.1+ / DirectX 9+ GPU.
• Persistent broadband connection.

Nintendo DSi has:

• ARM9 (133 MHz) + ARM7 (33 MHz) CPUs.
• 16 MB RAM.
• No Java runtime, no modern GPU, 256 KB browser cache.

What Does Work on DSi

• RuneScape Classic (2001–2004) — Java applet. DSi browser cannot run Java applets (no JVM).
• Homebrew: TWiLight Menu++ + nds-bootstrap runs NDS roms — not RuneScape.

Play RuneScape on Handheld Today

• Steam Deck / ROG Ally / Legion Go: Full PC client (Linux/Windows). Native controller support.
• Phone (Android/iOS): Official RuneScape Mobile — cross-progression with PC.
• Tablet: Same mobile app, larger screen.

DSi is a 2008 handheld. RuneScape is a 2024 live MMO. They don't meet.