In the classic APK files, weapon upgrades were earned via gameplay. The "old version" required a single download (often premium, but later made free with no strings). Modern versions are filled with $4.99 "Sniper Elite Packs" and VIP subscriptions that auto-renew.
Since downloading the APK alone won't get the game working, you'll usually need to find a paired OBB (data) file. For players on modern devices, there are community-crafted "fixed" versions available on forums like 4PDA or WeChat groups. These are pre-patched APKs that include a modified lib folder to support 64-bit processors. Additionally, if you find the in-app purchases frustrating, "mod" versions of the old game exist, offering "Unlimited Gold" or "Unlimited Money," allowing you to buy the best weapons without spending a dime. Frontline Commando D Day Game Download Old Version