Chess4D vs SheetTutor: Which Is Better in 2026?

Chess4D is a free browser chess site with three modes. 4D chess is played on a 4 × 4 × 2 × 2 hypercube board (64 squares) with X, Y, Z and W axes and legal-move markers, against a practice computer or a friend on the same device. 3D chess is standard 8 × 8 chess shown on a rotatable 3D board, played against Stockfish or two-player on one device, with move history and undo. 5D chess is an independent, experimental time-travel variant with branching timelines for two players sharing one device. Step-by-step rules and five guided 5D lessons are included. No download or account needed to play.

What problem it solves

Lets curious chess players try 4D, 3D and experimental 5D chess instantly in the browser, without installing anything or creating an account.

SheetTutor is a free Excel learning website built around small tasks that you complete in an editable browser worksheet. You can begin without creating an account, subscribing, or installing Microsoft Excel. The exercises give you a concrete question, source data, formula inputs and a result to check.

The learning examples use original datasets. Topics include SUMIFS and COUNTIFS with multiple conditions, exact lookups, text joining, weighted averages, and absolute or mixed cell references. You can inspect worked results, edit the provided worksheet, and download a matching workbook. The reference examples and the primary practice question are labelled separately, so viewing an answer does not itself count as completing the exercise.

For example, the COUNTIFS lesson asks you to count tickets that match a team, a status, and an age limit on the same row. Its primary question uses AND logic. Additional worked references compare disjoint OR, overlapping alternatives, and numeric intervals. One overlap example shows why adding two groups can count some rows twice, then subtracts their intersection to count each eligible source row once.

The COUNTIFS practice checks a reusable formula on the current worksheet and two additional original datasets. A constant result that only matches the displayed example does not demonstrate the task. Verification applies to the supplied data and stated input rules. The feedback distinguishes an incomplete attempt from a formula that gives an incorrect result on another dataset.

Calculations run in the browser, and analytics is optional. Downloads retain the example inputs and formulas so learners can inspect them outside the site. Browser verification, reference examples, full task assessment, and independent Microsoft Excel or Google Sheets compatibility are different claims. Native-client recalculation is recorded separately from browser checks and file downloads.

SheetTutor is maintained as an English learning resource. It is free to start practising and requires no signup. Submitted by the product maintainer.