Update 7/2/21
If anyone is considering purchasing a windows phone for the achievements, here is the experience I have had. I purchased a used lumia 550 on Amazon for 30 bucks. When it came in, it was almost useless, and it wouldn’t download anything. In the settings menu, I did a factory reset, which put it to version 1511. After that, I was able to perform several system updates to bring it to version 1709. From there, install the Xbox companion app from the store. Then you can install spartan strike and assault. Both are free if you have gamepass ultimate. I haven’t played Assault yet, but I was able to quickly get 15 of the 20 achievements from Strike last night. I had already completed the game on windows 8, so the assault ops and gold stars achievements popped after I completed 1 mission. I was also able to just complete mission 6 for each operation, and it gave me the achievement for completing the entire operation. Hint: each mission 6 also has a vid master achievement, so just knock those out at the same time.
I haven’t played Assault yet, but be sure to complete all assault ops on the Xbox 1 version before you play on windows 8, or windows phone. You can set the date back on the computer or phone to when there were weekly challenges, then complete 1 to unlock the assault ops achievement. If you complete the ops on windows 8, or windows phone first, I don’t think you can get the Xbox 1 achievement.
Original Post
Is it still possible to download Spartan Strike and Spartan Assault on a windows phone? I tried searching, but I couldn’t get a clear answer that was recent. I plan to purchase a compatible phone to complete the achievements, but if I can’t download the games anymore I didn’t want to waste my money. Thanks for the help