Word Puzzle

The achievement description is a little misleading, you do not need to get 50 combos in arcade, you need to get a streak of 50 combos. which means you need to get a 50 word combo in arcade. to get a combo find a word, then find another word before the gauge in the top left runs out.

Wallless Fury's description of the achievement is accurate. I'll just share my experience add some tips to help those who maybe struggling with this (like I was).

1. Pressing the Start button pauses the game and places a semi-transparent menu overlay (over) the game screen, but it does not block the list of words to find on the left. This maybe distracting but it does give you a breathing space to find the next word or figure out how many words are left to find.
2. Look out for the white high-lighted blocks which indicate either the front or last character of the word to be found. You can also see the high-lighted blocks behind the paused screen.
3. If in doubt, always pause the game, search the screen and plan the next word you want to find, using the high-lighted blocks as a guide. If you are unable to find the high-lighted blocks & time is running out, try to find words in the immediate vicinity to buy you some time.

Hope that helps. Surprisingly I managed to score this relatively easily, compared to the day before where I was frantically attempting this achievement several times.