This game has been around forever, and you (and /or your students) will probably be familiar with at least one version of it. I'll explain the simplest version first.
Each student is given a number (1 to 28 or similar - you can use higher numbers or a mix of non-consequetive numbers if your students are already pretty good with numbers.)
The teacher has a title (I use Pak Totomoto in Indonesian, my high school French teacher used Asherbanipal).
Start off by saying your title, then a number (eg, "Pak Totomoto, 2")
The student with that number then has to repeat their number and call someone else. (2, 18). And so on.
Any one who calls someone who is already out, or breaks one of the other rules you have put in place, is out. As students get more familiar with the game / vocabulary involved, you may want to add or tighten up rules.
The idea is to keep it quick - if a student takes too long they are out.
I suggest that you have a rule that restricts calling bask the person who called you, and watch out for students who just call the same number over and over.
You can also add a rule regarding mis-pronouncing words (I tend to give 3 chances here - but then you need to remember who has had a chance.)
An easy way to keep track of who is in and out is to write the numbers on the board (figures only) and cross them out as they get out. This way students can see also. You can make it harder by not letting the students see who is out.
* Add a rhythm (eg, click fingers, click fingers, clap. Need to say the numbers on the clicks. VERY hard with bigger numbers, at least in Indonesian!)
* Use different vocabulary. For this variation, I arrange the students in a circle. Each student is given a vocab item from a related set (eg, occupations or adjectives describing people). Students can either be given a picture that shows the meaning of the word, or can write their word clearly on a sheet of paper if you don't have pictures or you weren't planning on this game. They hold up the picture / sheet of paper while they are in, and place it flat or on the floor once they are out.
* Mix languages. Students say the first word (their own number / word) in English, then the second in the target language.
It can be useful to have something for students to do once they are out (eg a crossword or vocab activity on the words being drilled, or as "police" to watch for any over-long pauses etc), otherwise keep it really snappy.
You can also get a student to take over as the leader (Pak Totomoto)