Robot Coder Unblocked

Robot Coder turns programming into a planning puzzle. A small robot waits on a grid next to colored items and matching colored targets, and you have to write every instruction before it moves a wheel. When you press play, the program runs to the end with no chance to correct it. One step too many and the robot rolls into a wall. Schnark made it for the js13kGames contest in 2018, so the whole game fits in a tiny download, and it runs unblocked in any modern browser.

Commands, Items and Targets

Your program is a strip of symbols. The green arrow drives forward one square. The two curved arrows rotate the robot on the spot. The blue up and down arrows pick up and put down. Pickups and drops always act on the square directly in front of the robot, so it must face an item, not stand on top of it.

A level is complete when every item rests on a target of its own color. The robot can carry only one thing at a time, but nothing stops it from parking an item on a free square and coming back for it later.

Loops are the key to elegant code. A loop wraps a section of your program and repeats it between two and nine times. Four forward steps in a row become one loop with a count of four.

Robot Coder controls

To do this	Keyboard	Mouse	Touch
Step forward	Underscore (_)	Click the forward arrow key	Tap the forward arrow key
Rotate left or right	< or >	Click a turn key	Tap a turn key
Pick up or put down	Up arrow picks up, Down arrow drops	Click the up or down arrow key	Tap the up or down arrow key
Wrap commands in a loop	Type 2 to 9, then + or - to adjust	Click the loop key, then plus or minus	Tap the loop key, then plus or minus
Move the cursor or erase	Left/Right arrows, Home, End, Backspace	Click the cursor or delete keys	Tap the cursor or delete keys
Start the run	Enter	Click play	Tap play

Debugging Like a Programmer

Treat each failed run as information, not as a loss.

• Read the error. The game tells you whether the robot hit something, grabbed at nothing or dropped in the wrong place. That points straight at the faulty step.
• Slow the run down. A speed slider sits next to play, and the active symbol is highlighted as it runs. Watching at low speed shows exactly where your mental map and the real board disagree.
• Count facing, not just squares. After a left turn the robot faces a new way, and two turns spin it around completely. Many crashes come from losing track of direction.
• Solve first, then optimise. Get any program that works, save the checkmark, and only then hunt for repeated chunks you can fold into loops.
• Use temporary parking. Setting an item down out of the way can open a corridor the robot needs.

Who It Is For

Robot Coder is great for students meeting programming ideas for the first time and for experienced coders who enjoy code-golf style trimming. The command pad works with taps, so a phone held upright is enough, while desktop players can type programs on the real keyboard. Beeps for moving, turning and winning can be muted, and your shortest solution per level stays in your browser.

Once you finish the 24 levels, the editor lets you build maps up to 10 by 10 with walls, items and targets. For more puzzles that teach code thinking, try Block Code Maze or the elevator programming challenge in Elevator Saga.