Грай чесно.

Грай is the imperative form of грати (to play), used for one person in an informal way.

So it is the form you use when telling someone directly what to do:

• Грай! = Play!

In this sentence, it means play in the sense of giving an instruction.

Ukrainian often leaves out the subject when it is already clear from the verb form.

In грай, the imperative ending already shows that the speaker is talking to you (singular, informal), so a separate word for you is not needed.

English usually needs you only for emphasis:

• You, play fair.

Ukrainian normally just says:

• Грай чесно.

Because чесно is an adverb, and adverbs describe how an action is done.

Here, чесно tells you how to play.

Compare:

• чесний гравець = an honest/fair player
  
  • чесний is an adjective describing a noun
• грати чесно = to play fairly / honestly
  
  • чесно is an adverb describing a verb

So after a verb like грати, the adverb чесно is the correct form.

Its core meaning is honestly, but in this context it naturally means fairly, without cheating, or in an honest way.

So in a game, sport, or competition, Грай чесно. is the natural equivalent of Play fair.

In other contexts, чесно can also mean:

• honestly
• truthfully
• decently / honorably

Context decides which English word fits best.

You would say:

• Грайте чесно.

Грайте is the plural/formal imperative form. It is used:

• when speaking to several people
• when speaking politely to one person

So:

• Грай чесно. = to one person, informal
• Грайте чесно. = to several people, or to one person politely

If you want to make it softer, you can add будь ласка:

• Грайте чесно, будь ласка.

A rough pronunciation is:

• Грай ≈ hrai
• чесно ≈ CHES-no

A few useful details:

• г in Ukrainian is usually like a voiced h sound, not the hard English g
• ч sounds like ch in chat
• ай sounds like eye
• the stress in че́сно is on the first syllable

So the whole sentence is roughly:

• hrai CHES-no

Because грай comes from the imperfective verb грати, and that fits a general instruction about manner or behavior.

Грай чесно. means something like:

• play fairly
• play in a fair way
• when you play, do it honestly

A perfective form such as зіграй usually points more to a single completed action or one instance of playing. That is less natural for a broad rule like play fair.

So for a general instruction, грай чесно is the normal choice.

Yes, but Грай чесно. is the most neutral and natural order.

You may also hear:

• Чесно грай.

That version puts more emphasis on чесно. It can sound marked, emotional, or stylistically emphasized.

For a basic everyday instruction, verb + adverb is the safest pattern here:

• Грай чесно.

It is most naturally used for games, sports, and competitions, where the idea is don’t cheat.

But it can also be used more broadly in figurative contexts, for example if someone is behaving strategically or competitively in life, business, or politics. In that kind of usage, it means something like:

• act fairly
• play by the rules
• don’t cheat

Still, the most direct and ordinary reading is the literal one: someone is playing a game or competing.

By itself, it is a direct command, but not automatically rude.

It sounds natural when said:

• to a child
• to a friend
• during a game
• as a quick reminder

Depending on tone, it can sound:

• friendly
• firm
• accusing

If you want it to sound softer or more polite, you can say:

• Грайте чесно, будь ласка.

So the grammar itself is neutral; the tone depends a lot on the situation and intonation.