🕹️ Practice arcade
Extra games, not extra homework — timed sprints, survival runs that end when your lives run out, and mastery drills built from the same skills C# teaches.
⚡ Sprints
Beat the clock.
🐛 Bug-Hunt Time Trial
Two minutes. Each method has one bad line: a <= that runs off the end, an integer average, a stray semicolon, an if that assigns. Find it.
➗ Operator Sprint
Integer / and %, casts, ++ before and after, precedence, && and ||, and + with text. Evaluate it before the compiler does.
🔤 String Sprint
Trim that was thrown away, IndexOf and Substring, ranges and ^, Split with empty pieces, Join and Replace.
📚 LINQ Sprint
Where, OrderBy, Skip and Take in order; Count and Sum with a test; GroupBy's real order; and a query that sees changes after it was written.
💀 Survival
Each miss costs a life — lose them all and the run ends.
💥 Null, Throw, Crash
An unchecked as, FirstOrDefault, throw ex, a list changed mid-foreach, a Trim thrown away. Three misses and the service falls over.
⏳ Async Bug Survival
async void, .Result, a forgotten await, DateTime.Now in stored data, a counter two threads fight over. Three misses and you're out.
🗃️ Collections Survival
Shared arrays, Remove or RemoveAt, the indexer or TryAdd, Queue or Stack, and the right collection for the job. Three misses and you're out.
🎯 Mastery
No clock — just get N in a row.
🔍 Code Review
SQL glued from user input, a new HttpClient per call, interpolated log messages, a captive dependency, a 200 for a missing order. Catch five in a row.
🔁 Loop Tracer
switch sections, while and do, for-loop passes, break and continue: trace five in a row without an off-by-one.
🧭 Calls and Returns
Which argument changes, which overload wins, where a named or omitted argument lands, what a local function sees, and in what order a recursive method prints.
🧱 Classes at Work
Setters that clamp, properties that recompute, constructors that chain, base-class code that calls an override, and calls through an interface.
🏗️ Objects and Types
Static counters, constructor order, override versus new, struct copies, record equality and with, and class, record or struct.
✨ ?., Patterns and Lambdas
?. and ?? and ??=, first-match switch arms with < and <=, and what a lambda in a loop really captured.
🎯 Who Handles It?
When finally runs, which catch (and which when filter) takes the exception, and the order using closes things.
🩺 Read the Failure
Compile error, warning, runtime error or logic error? And which exception does this line really throw?
🧩 Design Choices
Transient, scoped or singleton; framework-dependent, self-contained, single-file or AOT; and which pattern the problem is asking for.