Atari 2600 Emulators for Android

Atari 2600 VCS emulator based on Stella 3.5-svn. Features include:

• Save state support, auto-save and ten manual slots for save states.
• Supports ROMs in .a26 and .bin formats, optionally in ZIP files
• Joystick and Paddle controller emulation
• Configurable on-screen multi-touch controls in addition to keyboard controls (needs Android 2.1+ for multi-touch, up to 3 touches supported at once), and an Xperia Play optimized button layout
• Multiplayer-capable Wiimote + Classic Controller, iControlPad, and Zeemote JS1 support (no need to purchase a separate app, see website for full instructions/compatibility)
• Portrait/Landscape auto-orientation support

RetroArch is an open source emulator interface for Android (and beyond). Read more: https://wikipedia.org/wiki/RetroArch. For emulation, you need to select and download the appropriate emulator kernels in the RetroArch interface.
There are emulator cores:

• 3DO
• Amstrad CPC
• Neo-Geo
• Atari 2600/5200/7800
• Atari Jaguar
• Commodore computers
• MSX
• Fairchild Channel F
• NEC PC Engine / CD
• Nintendo 3DS
• Nintendo 64
• Nintendo DS
• NES
• SNES
• Sega Genesis / Mega Drive / Sega CD / Mega CD
• Sega Master System / GG
• Nintendo Game Boy / Color
• Nintendo Game Boy Advance
• Sega Dreamcast
• Sega Saturn
• Sony PlayStation
• Sony PlayStation 2
• SNK Neo Geo Pocket / Color
• Sony PlayStation Portable
• MAME core
• Mednafen core

Full list on the project website. You can download RetroArch on Google Play or on the official website.