You have a three-litre jug, a five-litre jug, and one very specific goal: leave exactly four litres in the larger jug.
You can fill, empty and pour. There are no measuring marks to help you. Before you reach for a calculator, consider the real question: what sequence of moves would make that last pour possible?
If you are already moving water around in your head, River Crossing IQ has a promising invitation. Patcell’s illustrated puzzle adventure follows Sen through 42 handcrafted challenges across seven chapters, bringing river riddles, water measurements, number arrangements and spatial puzzles into a shared countryside setting.
The rebuilt version 5.0 is available on the App Store for iPhone and iPad. All levels and the game’s Solve with Sen guidance are free to play, including offline. Advertising and optional in-app purchases are included.
Simple rules. A surprisingly interesting next move.
A good logic puzzle can fit its rules into a few sentences and still give you something to think about. The water-jug challenge is an inviting example: the containers and target are familiar, but each action changes what you can do next.
Filling the larger jug is easy. Ending with the precise amount takes a plan. The puzzle asks you to pay attention to the water left behind, the space in the other jug and the order of your actions.
That is the appeal of this kind of game: an ordinary object becomes an interesting constraint. You do not need a complicated control scheme to start forming a hypothesis. You need a goal, a few rules and the willingness to reconsider an idea.
The solution is yours to discover. This introduction leaves the final sequence unspoiled.
Getting across is only half the question
The title’s river crossings introduce a different problem. A boat can carry something to the far bank—but it also has to come back. Your choice affects both sides of the river.
In one garden challenge, three sprouts and three jars need to cross in a boat that carries one or two items per trip. On either bank containing sprouts, jars must not outnumber them. Jars left on their own are safe.
Read that rule once, then imagine your first crossing. What have you left behind? Who—or what—will return? Is the next trip still possible?
The interesting moment is recognising that bringing something back can be part of making progress. A move that looks like a retreat may be exactly what the rest of the plan needs. The puzzle gives that idea a concrete form: two banks, a small boat and consequences you can see.
A journey with more than one kind of challenge
River Crossing IQ extends beyond boats and water. Its seven chapters include number puzzles, connecting paths, messenger birds, rolling stones and shape-placement challenges. Short stories and illustrated rules introduce the problems as part of Sen’s journey.
The lotus mosaic changes the way you look at a board. Seven pieces need to fit into a grid; you may rotate them, but never flip them. A shape can fit perfectly in one spot and still leave a space that makes the remaining pieces awkward.
Here the clues are not only the pieces in your hand. They are also the gaps you create. For players who enjoy switching between a precise sequence of actions and a visual arrangement, that variety is a reason to explore beyond the opening chapter.
A quiet setting for a busy mind
Sen’s straw hat and red scarf tie the journey together, with rivers, gardens, villages and lotus ponds inspired by the Vietnamese countryside. The official artwork pairs soft greens and warm cream backgrounds with clearly separated puzzle elements.
The setting gives the collection a sense of place without requiring any familiarity with it. English stories and rules are available, and the game also supports Vietnamese. The invitation is straightforward: read the situation, understand the constraint and try a move.
Undo lets you reconsider, while automatically saved progress lets you return after a break. For a little more direction, Solve with Sen offers free guidance. Optional specific hints use stars.
What you can play for free
According to the official App Store listing, all 42 levels and Solve with Sen work offline and are free to play. No registration is required to start playing or to purchase through the App Store.
The game includes ads. Optional purchases offer hint-star packs and removal of automatic ads; voluntary rewarded ads remain optional. Stars can also be earned through play. Purchases and online services require an internet connection.
Optional Game Center and iCloud support can restore puzzle progress on another Apple device. The listing explains the separate guest and signed-in star wallets, so players planning to change devices should read those details before doing so.
Which problem would you try first?
If you enjoy classic logic riddles, planning a few moves ahead or finding where a shape belongs, River Crossing IQ offers a collection worth exploring. Its questions are small enough to describe quickly, with room to pause and think about what each choice leaves behind.
Start with the two jugs. Or the boat. Or a mosaic with seven pieces waiting for a home.
River Crossing IQ is available now for iPhone and iPad. The next move is yours.
42 puzzles · Seven chapters · Free levels and guidance
Includes ads and optional in-app purchases.
Sources and images: River Crossing IQ on the App Store and Patcell’s official introduction. Product information checked on 21 October 2026. This is a promotional introduction based on official materials, not a scored hands-on review.
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