Of American-English origin, Simon says denotes a children’s game in which players must obey the leader’s instructions only if they are prefaced with the words Simon says; it also denotes the command itself. The name Simon was probably chosen for alliterative effect (Simon says).

The earliest instance that I have found is the following paragraph from the column of miscellanea, All Sorts of Paragraphs, in the Boston Morning Post (Boston, Massachusetts) of 25^th April 1842 (the game was already well known at that time, since it is implicitly referred to):

Simon is a great talker; sometimes he says “up,” sometimes he says “down,” and sometimes he says “wiggle waggle.” It is always cheapest to do as Simon says.

The second-earliest mention of the term is from The Pittsburgh Daily Gazette (Pittsburgh, Pennsylvania) of 6^th November 1848:

The bone of contention is who shall be United States Senator? There is a Whig majority of nine on joint ballot, and Simon Cameron’s term, as Senator, expiring, his place must be filled by somebody. A propos of Simon, the chief of the Winnebago branch of the democracy—politicians say that he is shelved at last, but I scarcely believe it. A man who could exemplify in his own person the tricks and quick turns of the youth’s game of “Simon says up, Simon says down, wiggle waggle,” and go through the motions so successfully, is not to be laid out so easy. His plots and counterplots with the Shunk dynasty [flat foots] and with the Porter influence [Kickapoos,] in all of which he held his own, will form in such an event, an important page in the secret history of Pennsylvania politics.

Many subsequent 19^th-century occurrences confirm the above-mentioned commands as well as their sequence. For example, the following, from The Memphis Daily Appeal (Memphis, Tennessee) of 3^rd June 1873, is about three candidates during an electoral campaign and the “wires” they are “pulling behind the curtain”; all three, says the journalist, are

very capable in the art of playing “Simon says up; Simon says down; Simon says wiggle-waggle.” Each has a large constituency, who “up, down, or wiggle-waggle,” as the particular wire is pulled, and in view of the approaching canvass they are “upping, downing, and wiggle-waggling” at a fearful rate.

An article in The Oregon Weekly Statesman (Salem, Oregon) of 31^st May 1871 even used the command wiggle waggle to describe one man named Simon:

Simon, not of wiggle-waggle fame.

Apparently, the noun wiggle-waggle also denoted a different children’s game. Outing. An Illustrated Monthly Magazine of Sport, Travel and Recreation (New York & London) of April 1895 published Spring in Rome, in which Leila Gittings wrote the following about foreigners buying objects at the market held on Wednesdays in the vicinity of the Farnese Palace:

When a choice is made the object is negotiated for largely by expressive pantomime. Brisk holding up of fingers and turning down of thumbs, like the children’s game of “wiggle-waggle,” forward a mutual understanding between buyer and seller.

The French equivalent of Simon says is Jacques a dit, meaning James has said.

The earliest occurrence that I have found is from L’Éducation physique au Patronage (Physical Education at the Youth Club), by Professeur H. Gasnier, published in La Vie au Patronage : Organe Catholique des Œuvres de Jeunesse (Édition pour garçons) (Life at the Youth Club: Catholic Organ of the Youth Charities (Boy Edition) – Antony: Union des œuvres ouvrières catholiques de France) of 15^th November 1925:

Jacques a dit (Jeu d’observation) — Placer les élèves de telle sorte qu’on les puisse bien voir tous à la fois. Puis leur expliquer le jeu et commencer.
Le jeu consiste à faire ce qu’on commande quand on fait précéder le commandement de :
« Jacques a dit », et à ne pas bouger quand le commandement est donné seul.
Exemple : Jacques a dit mains aux hanches, Jacques a dit mains à la nuque. Fixe.
Les élèves doivent exécuter les deux premiers commandements, puisque c’est Jacques qui l’a dit ; mais il ne doivent pas bouger au troisième, car ce n’est pas Jacques qui l’a dit.
Ce jeu est à la fois très amusant et très formateur.
Quand les élèves sont très exercés, on complique le jeu en exécutant soi-même tantôt ce que l’on commande, tantôt autre chose pour tromper.
     translation:
James has said (Observation game) — Place the pupils in such a manner as they can be well seen all together. Then explain the game to them and start.
The game consists in doing what is commanded when the command is preceded by:
“James has said”, and in not moving when only the command is given.
Example: James has said hands on the hips, James has said hands on the nape of the neck. Eyes front.
The pupils must execute the first two commands, since it was James who said it; but they must not move at the third, for it was not James who said it.
This game is at the same time very amusing and very formative.
When the pupils are well-trained, the instructor makes the game more complex by executing himself sometimes what he commands, sometimes something else to deceive.

The French novelist and critic Paul Bourget (1852-1935) mentioned the game in Le Louveteau (The Cub Scout – Paris, 1932):

« Un Jacques a dit… » Ce terme sibyllin désignait un des exercices favoris des louveteaux. La cheftaine leur crie : « Jacques a dit… » et ordonne un geste : s’asseoir, lever le bras, ouvrir la bouche, puis brusquement elle commande un autre geste, mais sans le précéder du « Jacques a dit » [&c.].
     translation:
“A James has said…” This sibylline term designated one of the Cub Scouts’ favourite exercises. The captain cries out to them: “James has said…” and orders a gesture: to sit down, to raise the arm, to open the mouth, then suddenly she orders another gesture, but without preceding it with the “James has said” [&c.].