Clash of Clans team officially has announced that Clash of Clans (COC) won't support operation systems lower than Android 4.4 and iOS 10 in the next update to Clash of Clans (later this year) because of technical reasons. If you play COC on those systems, COC team suggest upgrating systems to higher in case you can't play COC any more on old systems.
For COC players on Android, check Google's official support to upgrade your systems.
For players with iOS, visit Apple Support Center to upgrade.
If you plan to switch devices, follow How do I Transfer Clash of Clans Data? (Android/iOS/iPhone/ iPad) to save data.
After you upgrade or switch devices, you can continue to enjoy the game as before. If you are looking for a helper for COC to automatically play the game for you, COC Bot is the tool you won't miss as it features automatical collecting resources, searching dead base and defeating enermies.