See Material Gambit for notes on the Gambit cycle.

This one is a bit reminiscent of Primal Growth. Since the opponent gets the choice whether you sac or not rather than you doing so, the cost is lower, and I gave you 3 lands in the "kicked" case; however 2 of them had to go into hand.

This might not be the most obvious green effect for a gambit, but green needs some mana-search/ramp spells in a set, and finding Code Geass-suitable flavour for them is tricky. "Positional Gambit" I think is a name that can suit gaining some land, so I'm grabbing the opportunity. (Pity the cycle has to be uncommon for complexity.)

The whole cycle seems to be working out as having the "gambit-refused" option be a common staple spell that's 1 mana cheaper. Search for Tomorrow is the card in this case (or the bizarrely-uncommon Untamed Wilds), but those are so obscure that it's easier to think of the gambit-refused option as a Rampant Growth that gets the land untapped (like Land Aid '04).

Also, bleh this is wordy. Due to the long template for "search... put onto the battlefield... then shuffle your library" getting duplicated. Inevitable, but annoying.

I do think making it a common spell 1 cheaper is risky. I mean, sure; your opponent might make you sacrifice a creature. If you're daft enough to cast this when you've got one big creature.

I don't think that limit is really strong enough to make a mana cost reduction safe.

But, well, it's a bog standard ramp spell. What harm could it do?

... thinking harder, and more gambitier (and more 'lelouche is a douchebag'); you could make "Sacrifice a creature" be your choice. Form then being:

Normal effect. When you cast this, you may sacrifice a creature. If you do opponent chooses either: * You take this card back into your hand. * Second stronger effect.

But, meh, words words words.

Well, the thing about a gambit in actual chess is that it's an offer of a pawn (ie moving a pawn into a position from where it can be captured without repercussions); the opponent may decline the offer. So I'm not convinced your version is gambitier. (Even though that should definitely be a word.)

However your version does have the arguable upside that it can be keyworded:

> Search your library blah blah basic land blah shuffle.
> Gambit. (You may sacrifice a creature. If you do, an opponent chooses one -- either return this card to your hand; or [some other bonus])

...mm, no, typing that out I realise that if the other bonus is to vary by colour, then it needs to be an ability word, which doesn't save as much mindspace:

> Gambit - You may sacrifice a creature. If you do, an opponent chooses one -- either return this card to your hand; or [some other bonus].

What about this?
Positional Gambit
Sorcery
Search your library for a forest card and put it onto the battlefield, then shuffle your library.
Gambit— An opponent may have you sacrifice a creature. If a player does, instead search your library for two land cards, put them onto the battlefield, then shuffle your library.

Or this:
­Positional Gambit
Sorcery
Gambit (You may risk a creature you control as you cast this.)
Return target land from your graveyard to the battlefield.
If you risked a creature, target opponent chooses one— You sacrifice the risked creature and return ~ to your hand; or return up to two additional land cards from your graveyard to the battlefield.

Thanks for the suggestions! :)

If the choice is an opponent's, then I don't want the non-risked version to be Nature's Lore, because then the card as a whole is strictly worse than Nature's Lore.

The version with "You may risk a creature" switches it round again to provide choice on both players' part... even more confusing.

I don't really like Restore, and I'd only want to print it in a set with some significant discard / mill / land-sacrifice theme. Good for Vitenka's "Llanowar Burned", but not so much what I want. It is a clever way of making a sorcery that's not so much a problem if you get to cast it several times, though.

But I do like the "Gambit — An opponent may have you sacrifice a creature. If a player does," wording.

I didn't mean to suggest the actual card texts as much as I did the ideas for gambit. Those are just filler I was using to demonstrate.
I agree that the version with gambit as a keyword led to a very confusing card with lots of options. I just liked "you may risk a creature as you cast this." I wonder if there's something better that could be done with that.