Change the voice: Let us play together.

It is suggested that we should play together

It was suggested that we should play together

It will be suggested that we should play together

It should be suggested that we should play together

Active Voice: Let + us + first form of a verb.

Passive Voice: It is suggested + that + we + should + first form of a verb.

Active Voice: Let us play together.

Passive Voice: It is suggested that we should play together.